Preheat your oven to 180 C / Gas 4.

Place your sliced apples evenly over the base of an oven dish of roughly 30x20cm or a little smaller. Mix the caster sugar, 1 tablespoon of plain flour and cinnamon together and sprinkle over the apples. Pour the water over the apples.

For the crumble topping combine the oats, 125g of flour, brown sugar, baking powder, baking soda and melted butter in a bowl using a dessert spoon. I find that you can use it to “break” the mixture up so that it looks more like a crumble mix once it’s all combined. Sprinkle it over the top of the apple mix evenly.

Bake in the oven for 45 minutes. Once baked remove and set aside to cool completely. Leave the oven on.

Grease the same size of oven dish of roughly 30x20cm or a little smaller.

In a large bowl beat the sugar, butter and vanilla extract together until light and fluffy. Add the eggs one at a time, beating each one in until well combined as you go.

Sift in the flour, cocoa, salt and baking powder. Gently fold this into the mixture until well combined. You don’t really want to beat this in, you just want to get it well combined.

Divide the brownie mixture into two separate bowls. Add the first half into your prepared baking tin and spread evenly. Get your apple crumble and break it up a little. The idea here is that you don’t want to get bits of crumble topping in places and just apple in others, you want to spread it evenly without letting it sink. Don’t get right to the edges of the mixture but go as close as you dare.

Finally, spoon over the remaining brownie mixture over the top of the crumble and carefully spread it evenly.

Pop into the oven and bake until the surface no longer looks wet, about 25 minutes. Brownies don’t “firm up” in the middle but the surface shouldn’t be moist.

Let them cool in the tin and serve as you like, either warm or completely cooled.