Preheat your oven to 350°F/180°C. Line a 9x13inch (23x33cm) pan with parchment paper or well-greased foil and set aside.
Put half the oats into a food processor and pulse until they're finely chopped (you're looking for the texture of instant oats or porridge oats). Tip into a large bowl with the whole rolled oats.
5 cups rolled oats
Put the sunflower seeds, pumpkin seeds, raisins and apricots into the food processor bowl, and pulse so the seeds are coarsely chopped and the fruit pieces are all roughly the size of half a raisin. You don't want to chop too finely, but you do want it to mix through the granola bars evenly and easily. Tip into the bowl with the oats and mix well.
1/3 cup sunflower seeds, 1/2 cup pumpkin seeds, 1/2 cup raisins or sultanas, 1/2 cup chopped dried apricots
Put the butter, sugar, honey, salt and 2 tablespoons of water into a saucepan and melt together over medium heat. Stir occasionally so it doesn't catch, and so the butter mixes in smoothly as it melts. Take the mixture off the heat when the sugar is fully dissolved and everything has come together in a smooth syrupy consistency.
1 stick unsalted butter, 1 cup superfine sugar, 1/3 cup clear honey, 1/4 tsp fine salt
Immediately pour the hot sugar/syrup over the dry ingredients and mix thoroughly. It's going to take a while to get the syrup worked through all the oats, and it'll seem like there's not enough wet ingredients to make it come together. Have patience and keep mixing until there are no more dry bits!
Spread the mixture out evenly in the prepared pan and compress it down really well with the base of a glass. Don't skip this step, compressing the mixture into the pan means your bars will cut more cleanly after baking. Bake until the mixture is lightly golden all over the top, about 25 minutes.
Remove from the oven and cool completely in the pan before lifting out using the paper. Cut into bars with a sharp serrated knife. I put the cooled bars in the fridge for an hour or two before cutting, to get the cleanest cuts.
Your granola bars will keep in an airtight container at room temperature for a few days, or in the freezer for 2 months.