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12 minute steam oven brownies
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4.8 from 5 votes

Brownies with Salted Peanut Butter Frosting (only 12 minutes to cook!)

These amazingly deep, dark and fudgy brownies take only 12 minutes to cook in a steam oven, and they're topped with creamy, soft and salty peanut butter frosting.
Prep Time15 mins
Cook Time12 mins
Total Time27 mins
Course: Afternoon Tea, Dessert
Cuisine: American
Keyword: brownies, brownies with salted peanut butter, steam oven brownies
Servings: 20 brownies
Calories: 255kcal


For the brownies

For the frosting

  • 3.5 oz unsalted butter softened
  • 3/4 cup smooth peanut butter Now is not the time to go all natural, salt and sugar free, people. Skippy or Kraft is just fine.
  • 1 cup confectioners sugar icing sugar
  • 1 tsp flaky sea salt Maldon is my preference; use a little less salt to start with and add to preference


Make the brownies

  • Grease and line a 8"/20cm slice or cake pan, making sure your lining paper extends over two sides for ease of lifting later. Preheat your oven to 320˚F/160˚C, combination steam setting. If your oven has variable steam settings, use 80% steam. If not, don't worry! Just set to combination steam at the correct temperature and the oven will figure out the humidity for you.
  • Pu the butter in a small saucepan over medium heat. Let it melt and then come to the boil and cook, swirling the pan frequently, until it's stopped foaming and the milk solids begin to brown. It will take about 5 minutes, and you'll know it's close when the foamy bubbles on top give way to smaller more distinct bubbles. It'll smell like caramel and nuts and the solids will drop to the bottom and change colour. Take it straight off the heat and pour into a heatproof bowl to avoid burning it.
  • Add the chocolate to the hot butter and leave it to sit for a couple of minutes so the chocolate can melt. Stir to combine, then whisk in the sugar and vanilla. Leave to cool slightly, then add the eggs and mix well (adding them when it's too hot will leave you with scrambled eggs in your batter).
  • Sift the flour and cocoa into the bowl and add the salt. Stir gently until everything is combined, then pour into the lined pan.
  • Bake for 12 minutes, or until the top is set and a skewer tests clean in the centre of the tray. Remove from oven and leave to cool completely in the tin before spreading the frosting over the top.

Make the frosting

  • To make frosting, put all the ingredients in the bowl of an electric stand mixer fitted with the paddle attachment. Beat for 3-4 minutes on medium speed, until the frosting is light and fluffy. I'd recommend starting out with 1/2 tsp salt in there and gradually adding more to taste if you want it.
  • Serve cut into squares or bars; I cut into 20 pieces but you decide how big you want yours to be! The brownies will keep, covered, at room temperature for a couple of days, or in the fridge for about 5 days.


  1. A note on browned butter: if you haven’t been introduced to the joys of nutty, toasty browned butter in baked goods yet, you’re welcome. Also, I’m sorry, because if you’re like me, once the discovery’s been made you won’t be able to just leave things alone and will be substituting it for regular melted butter in all sorts of delicious places. Namely: brown butter chocolate chip cookies, brown butter pound cake, spiced pumpkin cake with brown butter, brown butter cookies...
  2. A note on the frosting: I suspect thanks to life in a warm climate, I found my first batch of frosting soft to the point of melting off the brownies. I’ve revised ingredient quantities to stiffen it up somewhat but didn’t want to lose the lovely soft texture altogether. Because of this I’d recommend not stacking the cut brownies on top of one another for serving/storage (unless they are fridge-cold), or you’ll end up with a brownie layer cake. Also, if you want nice clean-cut pieces, you’ll need to chill the whole slab before cutting with a hot knife to prevent the frosting smudging.
  3. Though a lot of baked goods are best served at room temperature, I actually prefer these slightly cooler so the brownie is almost like a piece of fudge in texture.


Calories: 255kcal | Carbohydrates: 23g | Protein: 5g | Fat: 17g | Saturated Fat: 9g | Cholesterol: 54mg | Sodium: 239mg | Potassium: 147mg | Fiber: 2g | Sugar: 16g | Vitamin A: 372IU | Calcium: 17mg | Iron: 1mg