PREPARE: Heat the oven to 180°C / 350°F / Gas 4. Line the base of a 20cm round spring form cake tin with baking paper and grease the base and sides well with butter.

MAKE THE CRUMBLE: Make the crumble by combining the flour and butter in a bowl. Use your fingers to rub the butter into the flour, pinching it and squeezing it until it has a rough, pebbly texture. It doesn’t have to be fine, in fact, the rougher the better. Stir through the sugar and nuts, then put the bowl in the freezer while you prepare the cake.

MIX THE BATTER: In a mixing bowl, whisk together the sour cream, eggs and oil until smooth. In a separate bowl whisk together the flour, sugar, baking powder and cinnamon until well combined. Stir the wet ingredients into the dry until just combined, then add the apple cubes to the mixture and fold through, gently but thoroughly. Scrape the mixture into the prepared tin, smooth the top, then scatter over all of the crumble.

BAKE: Bake in the bottom third of the preheated oven for 1 hour. Check around 55 minutes to make sure it isn’t getting too brown on the top, it shouldn’t, but if it is, cover loosely with a square of tin foil. After an hour, check to make sure the cake is cooked by inserting a wooden skewer into the centre of the cake. It should come out with just a few moist crumbs clinging to the skewer. If it is at all liquid, return to the oven for a further 5 minutes.

COOL AND SERVE: Allow the cake to cool in the tin before running a sharp knife around the side to loosen from the tin and transferring to a serving platter. Dust with icing sugar to serve, and if you fancy a big mound of whipped cinnamon cream, though it is so lovely and moist the cake doesn’t need it.