Leek and Mushroom Tart (regular oven and combi steam oven methods)

This post includes affiliate links. Find out more about affiliate links and how they help this site.

A leek and mushroom tart is a great meat-free way to get a deeply satisfying meal on the table and with the method I’m going to show you today, it takes far less effort than you might imagine. That’s because the tart is baked upside down, so it’s low on fuss and big on crispy pastry and silky vegetables!

My leek and mushroom tart can be made in a regular oven or a combi steam oven (which will do magical things to your puff pastry, making it ultra flaky and crispy). Either way you’re going to love how simple it is to make, and if you’re like me you’ll start thinking of all the other kinds of upside down tarts you can make using this method. Roasted pumpkin and caramelised onion? Chorizo and cauliflower? Sausage and fennel? So many combinations, so many opportunities to eat pastry for dinner. Ha.

Why bake an upside down leek and mushroom tart?

There are a few reasons I love an upside down mushroom tart over a normal right-way-up one.

Firstly, when the tart is upside down, it’s hard to overcook the filling because it’s protected by the pastry which sits on top during baking. And when it comes to that pastry, there’s no wet or heavy filling sitting on it, stopping it from cooking properly. That makes for the puffiest and flakiest tart base imaginable when it gets turned out for serving.

Here’s my favorite reason for baking upside down tarts though: I can cook the filling and the tart in one pan for minimal washing up. Nothing motivates me quite like the ability to cut down on dishes when I’m creating a recipe!

Baking pastry in a combi steam oven vs a regular oven

I mentioned above that you can bake this mushroom and leek tart in a regular oven or a combi steam oven. A regular oven is just fine here and your pastry will still be flaky, puffed and golden, but if you have the option of combi or convection steam now’s the time to use it!

Puff pastry and combi steam cooking are an unlikely pair but they make incredible friends. The dry heat in your steam oven will crisp and brown the pastry’s exterior just like a regular oven, but the added steam while cooking makes the layers of puff pastry separate beautifully, turning them into something extra flaky, tender and, well, puffy.

What kind of mushrooms do you use in a mushroom tart?

You’ll see from today’s photos that I’ve gone with button mushrooms for my tart. They’re mild in flavor and very easy to find most places, so they’re a good everyday choice if not the most ‘mushroomy’.

If you’re devoted to seeking out fancy mushrooms, almost any type will work here except the long, thin enoki mushrooms, which get a bit stringy and tough in the oven. I’ve made this tart several times now and despite the button mushrooms in the pictures, my favorite type of readily available mushrooms to use are the large flat or field mushrooms. They have a bigger flavor and the texture becomes a bit softer and silker when they cook down than the button mushrooms.

To really boost the depth of flavor you can add some soaked and chopped dried porcini mushrooms. I’ve done this a couple of times and it makes the tart really earthy, savory and rich.

How to make a leek and mushroom tart

Hopefully I’ve convinced you to give this recipe a try! Here’s how to make your leek and mushroom tart.

 Mushrooms, leeks, thyme, garlic and butter in a pan ready to be sauteed for leek and mushroom tart.

You’ll need sliced leeks and mushrooms along with garlic, thyme and a good knob of butter. If you’re using a regular oven to bake your tart, you’ll need to start off by cooking the filling on the stove – sauté the leeks and mushrooms in the butter until they’re softened. In a combi steam oven, you can skip the stove and put the pan straight in the oven to begin cooking your vegetables.

 Adding sherry, salt and pepper to partially cooked leeks and mushrooms in a large pan.

Once the leeks and mushrooms are soft, add salt, pepper and dry sherry (the sherry is optional but you won’t get the same flavor without it), then cook until the sherry evaporates and the vegetables have softened further and reduced in volume by about two thirds.

 Cooked leek and mushroom tart filling in a cast iron pan.

 Uncooked puff pastry, laid over the top of leek and mushroom tart mixture in a pan, ready to bake.

Now, working quickly, you’re going to lay a sheet of puff pastry over the leek and mushroom mixture, tucking it around the edges kind of like you’re putting it to bed. Get it straight into the oven and then sit back and wait for the puff pastry to do its magic, rising and turning flaky and golden.

 Cooked upside down leek and mushroom tart, in the pan ready to turn out and serve.

Once your tart is cooked, remove it from the oven and put an upturned plate or chopping board over the top of the pan. Carefully flip everything over and lift off the pan, revealing the finished tart underneath! This is the most nerve wracking part of the whole recipe, but as long as you’re organized it’s fine.

 Upside down leek and mushroom tart on a chopping board, ready to slice and serve.

My top tips here are to make sure your hands are well protected by pot mitts or kitchen towels, and lift the pan tilting away from your face – a fair amount of scalding steam will come out as you lift the pan off the tart and you don’t want steam burns.

You’ll almost certainly find there are a few bits of leek and mushroom left behind in your pan after turning out the tart, just pick those up with tongs and pop them back onto the tart. No one will be the wiser.

Beautiful! Serve your masterpiece immediately with dollops of room temperature mascarpone cheese (or sour cream if you prefer), which will add a creaminess to offset the deep flavors of the filling and the crunch of the pastry. I like to add a sharply dressed green salad when I serve this too, just to brighten everything up.

Happy cooking, see you here again soon.

 A leek and mushroom tart, served on a white platter with a spoonful of mascarpone cheese and fresh thyme leaves scattered over the top.

 

Print Recipe
5 from 2 votes

Leek and Mushroom Tart

A simple, savory vegetarian leek and mushroom tart with a difference: it’s baked upside down to ensure crispy pastry and a silky, tender filling!
Prep Time10 mins
Cook Time30 mins
Total Time40 mins
Course: Appetizer, Main Course, Side Dish
Cuisine: Western
Keyword: leek and mushroom tart, mushroom tart, steam oven tart
Servings: 4
Calories: 449kcal

Ingredients

  • 2 tbs butter
  • 1 lb mushrooms 450g (see note), sliced or torn into thick pieces
  • 2 leeks halved lengthways and sliced (discard green tops)
  • 2 stalks thyme fresh, leaves picked
  • 2 cloves garlic minced
  • 2 tbs dry sherry
  • 1 tsp salt
  • ¼ tsp ground black pepper
  • 1 sheet puff pastry frozen, 12in/30cm squares, thawed
  • 4 tbs mascarpone cheese optional, to serve

Instructions

Conventional Oven Method

  • Preheat oven to 200°C/400°F.
  • Heat an ovenproof 12in/30cm round heavy based pan over medium heat. Add the butter and let it melt, then put in the mushrooms, leeks, thyme and garlic and increase the heat to medium high. Cook, stirring occasionally, until the mushrooms have softened and shrunk a little. Add the sherry, salt and pepper, and continue cooking until the leeks are quite soft and the mushrooms have cooked down to about a third of their volume. It’s fine if there’s a little liquid in the pan, but the vegetables shouldn’t be swimming. If the leeks are starting to brown before the mushrooms are cooked, reduce the heat slightly to stop them burning.
  • Remove the pan from heat and lay the pastry directly over the top of the mushroom mixture to completely cover it. I trim the corners of the pastry to fit the pan, though you could just tuck them in a bit if you aren’t worried about presentation.
  • Put the pan in the oven and cook until the pastry is puffed and golden, around 20-25 minutes. Remove from the oven and immediately invert onto a large plate or a board for serving. Scoop up any vegetables which get left behind in the pan and put them back onto the tart.
  • Slice into pieces and top each piece with a scoop of mascarpone cheese to serve (the mascarpone isn’t essential but it adds a lovely richness). Serve hot or warm with a vinegar and mustard-dressed green salad alongside.

Combi Steam Oven Method

  • Preheat oven to 200°C/400°F, combination steam setting. If your oven has variable steam, select 50% (if you don’t have variable steam, just select combination or convection steam setting at the correct temperature, and the oven will work out the humidity for you).
  • Put the butter, mushrooms, leeks, thyme and garlic into a 12in/30cm round heavy based pan, or a 9x13in/23x33cm rectangle pan. Give it a quick stir but don’t worry too much about everything being mixed perfectly.
  • Put the pan into the preheated oven and cook for 5 minutes, then stir to mix the now-melted butter through. Add the sherry, salt and pepper, mix briefly again, then return the pan to the oven for a further 8-10 minutes, or until the leeks are quite soft and the mushrooms have cooked down to about a third of their volume. It’s fine if there’s a little liquid in the pan, but the vegetables shouldn’t be swimming.
  • Remove the pan from the oven and lay the pastry directly over the top of the mushroom mixture to completely cover it. If you’re using a round pan, you can either trim the corners of the pastry to fit the pan, or just tuck them in a bit if you aren’t worried about presentation. In a rectangle pan you’ll have to push the mushroom mixture towards the center of the pan to make a square mound of vegetables that’ll fit under your pastry sheet.
  • Return the pan to the oven and cook until the pastry is puffed and golden, around 12-15 minutes. Remove from the oven and immediately invert onto a large plate or a board for serving. Scoop up any vegetables which get left behind in the pan and put them back onto the tart.
  • Slice into pieces and top each piece with a scoop of mascarpone cheese to serve (the mascarpone isn’t essential but it adds a lovely richness). Serve hot or warm with a vinegar and mustard-dressed green salad alongside.

Notes

  1. Serves 4 as a light meal.
  2. Use any mushrooms you like here, except enoki (which are too stringy once they’ve been cooked in the oven).
  3. I buy square sheets of pre-rolled puff pastry from the freezer section of my supermarket. Feel free to buy a block and roll it out yourself, or to make your own (it will undoubtedly be more amazing than my mass-produced stuff!).
  4. Do be careful turning this tart out after baking. It’s not a difficult job, but you do need to be careful flipping and lifting the pan away from the tart so you don’t end up with a face full of steam.
  5. The nutritional calculations for this recipe have been done without the optional mascarpone cheese.

Nutrition

Calories: 449kcal | Carbohydrates: 39g | Protein: 9g | Fat: 30g | Saturated Fat: 10g | Trans Fat: 1g | Cholesterol: 15mg | Sodium: 799mg | Potassium: 496mg | Fiber: 3g | Sugar: 5g | Vitamin A: 942IU | Vitamin C: 9mg | Calcium: 44mg | Iron: 3mg

Over to you – if you try this recipe I’d love to know about it! Share your comments below or on Facebook, tag @steamandbake on Instagram, or pin all your favourite Steam and Bake recipes over on Pinterest!

Would you like more recipes and tips to help you cook with confidence? Join the mailing list to be alerted to new posts.

Related:

Classic Apple Tarte Tatin

Cannelloni with Spinach, Ricotta and Mushrooms

Vegetarian Sausage Rolls

1 thought on “Leek and Mushroom Tart (regular oven and combi steam oven methods)”

  1. Pauline Marks

    5 stars
    Easy recipe which works every time. Very tasty and definitely recommended

Leave a Comment

Your email address will not be published.

Recipe Rating




Scroll to Top