Preheat your oven to 180°C and grease your cake tin with a little bit of butter. Line the bottom and sides with non-stick baking paper to ensure the cake comes out very cleanly.

Sift the self-raising flour, baking powder, and ground cinnamon into a large mixing bowl with care. Cinnamon is a brilliant addition because it enhances the natural sweetness of the fresh, juicy cooking apples.

Place the softened butter and caster sugar into a separate bowl and beat them until very light. You want the mixture to look pale and fluffy before you start adding the eggs to the mix.

Beat the large eggs into the butter mixture one at a time to prevent the batter from curdling. If the mixture starts to separate, add a spoonful of flour to keep it smooth and very creamy.

Fold the sifted flour mixture into the wet ingredients using a large metal spoon or a silicone spatula. Stir gently so you do not knock the air out of the sponge batter during this important step.

Peel, core, and chop the cooking apples into small, even chunks using a sharp vegetable knife. Smaller chunks ensure that the fruit is distributed evenly throughout the cake and cooks through very nicely.

Fold the apple chunks and the milk into the thick cake batter until they are well combined. The milk helps loosen the mixture just enough so it spreads easily into the corners of the tin.

Spoon the apple cake mixture into the prepared tin and level the top with the back of a spoon. Sprinkle the demerara sugar over the surface to create a very crunchy and sweet golden crust.

Slide the tin into the oven and bake for forty-five to fifty minutes until the sponge is firm. A skewer inserted into the center should come out clean without any wet batter sticking to it.

Let the cake cool in the tin for ten minutes before transferring it to a wire rack. Serve it warm with a dollop of cream or a scoop of vanilla ice cream for dessert.