Heat the oven to 180C/160C fan/gas 4. Lightly butter a 900g loaf tin and line with baking parchment. Peel and core the apple, then cut into roughly 1cm cubes.

Using an electric whisk, beat the butter and both sugars in a large bowl until very pale and fluffy. Beat in the eggs, one at a time, beating well after each addition. Add a little of the flour if the mixture looks like it's about to curdle. Fold in the remaining flour, the cinnamon or mixed spice and a pinch of salt using a spatula, then fold in the apples.

Scrape the mixture into the prepared tin and smooth out with the back of a spatula or spoon to level. Bake for 1 hr, or until risen and golden, and a skewer inserted into the middle of the cake comes out clean.

Leave to cool completely in the tin. Will keep in an airtight container at room temperature for up to three days.