Prepare the blueberry layer by combining 400g frozen blueberries, lemon zest, 10ml lemon juice, and 50g demerara sugar
Make the sponge by creaming together 200g brown butter, 100ml neutral oil, and 280g caster sugar
Beat in 3 large eggs one at a time
Fold in sifted 250g plain flour, 75g potato starch, 1.5 tsp baking powder, 0.25 tsp bicarbonate of soda, and a pinch of salt
Add 1.5 tsp almond extract and 1 tsp vanilla bean paste
Mix in 100g cottage cheese, 15ml whole milk, and a squeeze of lemon juice until combined
Prepare the crumble by combining 100g plain flour, 60g diced salted butter, and 30g caster sugar
Layer the blueberry mixture in the cake tin, top with sponge batter, and sprinkle with crumble
Bake until golden and cooked through
Serve slightly warm with custard or enjoy the next day with coffee
