Prepare the tin – Grease the cake tin thoroughly and line the base and sides with baking parchment. Preheat the oven so it reaches a steady temperature before baking, which helps the cake rise evenly.

Make the sponge base – Beat the softened butter and caster sugar together until pale and fluffy. This step incorporates air into the mixture, giving the cake a lighter texture.

Add the eggs gradually – Beat in the eggs one at a time, mixing well after each addition. This prevents curdling and keeps the batter smooth and stable.

Incorporate the dry ingredients – Sift in the self-raising flour and baking powder, then fold gently with the milk. Mix only until combined to avoid a dense sponge.

Prepare the apples – Toss the diced apples with lemon juice to stop them browning and to balance their sweetness. Cut them into small, even pieces so they soften evenly during baking.

Assemble the cake – Fold the apples gently through the batter, then spoon the mixture into the prepared tin and level the surface.

Bake until set – Bake on the middle shelf until the cake is golden, springy to the touch, and a skewer inserted into the centre comes out clean.

Make the toffee sauce – While the cake bakes, melt the butter, brown sugar, golden syrup, and cream together gently in a saucepan. Stir until smooth and glossy, without boiling.

Finish with toffee – Pour the warm toffee sauce evenly over the cake while it is still warm. Let it soak in before slicing.