Prepare the apple filling: In a small bowl, toss the diced apples with the light brown sugar, ½ teaspoon of the cinnamon, and a pinch of nutmeg. Set aside for 10 minutes — you should see the apples begin to release their juices, turning glossy and fragrant.

Make the crumble topping: In a separate bowl, rub together the cold butter cubes, rolled oats, demerara sugar, and remaining ½ teaspoon of cinnamon until the mixture resembles coarse breadcrumbs. Some larger clumps are fine — they'll create those lovely craggy bits on top. Pop it in the fridge while you work on the cake.

Create the creamy cake batter: In a large mixing bowl or stand mixer, cream together the 100g butter and caster sugar until pale and fluffy — about 3 minutes. The mixture should look light, almost mousse-like, and smell sweetly of butter. Beat in the eggs one at a time, then add the vanilla extract. The batter might look slightly curdled at this stage; don't panic, that's normal.

Fold in the dry ingredients: In a separate bowl, whisk together the flour, baking powder, bicarbonate of soda, remaining ½ teaspoon cinnamon, ¼ teaspoon nutmeg, and salt. Add half the dry mixture to the wet mixture, followed by half the Greek yoghurt, and fold gently. Repeat with the remaining flour and yoghurt. Stop as soon as the streaks disappear — overmixing will make the cake tough. The batter should be thick, creamy, and smell wonderfully tangy.

Layer the cake: Preheat your oven to 180°C (160°C fan) and line a 20cm round springform tin with parchment paper. Spread half the cake batter into the tin — it will be a fairly thin layer. Spoon the macerated apples evenly over the batter, leaving a 1cm border around the edge. Dollop the remaining batter on top, then carefully spread it to cover the apples. It's fine if a few apples peek through.

Add the crumble: Sprinkle the chilled crumble mixture generously over the top of the cake. Use your fingers to create some larger clusters — these will toast beautifully and give a professional, rustic appearance.

Bake to golden perfection: Place the tin on the middle rack and bake for 45–50 minutes. At the 35-minute mark, check the top — if the crumble is browning too quickly, tent loosely with foil. The cake is ready when a skewer inserted into the centre comes out clean or with a few moist crumbs, and the top is a deep golden brown. Your kitchen should smell of spiced apples and toasted oats.

Cool and rest: Remove from the oven and let the cake rest in the tin for 15 minutes. This step is crucial — the creamy interior needs time to set, or it will collapse when sliced. After 15 minutes, transfer to a wire cooling rack to cool completely. The cake will settle into a beautiful, even dome.

Plate with flair: Once completely cool, dust lightly with icing sugar through a fine sieve. For a restaurant-style finish, I like to serve each slice on a warmed plate with a drizzle of double cream or a scoop of good-quality vanilla ice cream. A small sprig of mint or a dusting of extra cinnamon on the plate edges elevates the whole experience.