Parkin – spiced oat cake with golden syrup and black treacle

Preheat the oven to 160°C with top and bottom heat. Line a square tin about 22 cm across and at least 5 cm deep with baking paper, leaving edges overhanging so you can lift out the cake later. There is no need to grease it as well. Weigh all the ingredients; measure the eggs without their shells and weigh the milk.

Put the oats in a food processor or mini chopper and pulse briefly a few times to make coarse particles, without grinding them into a smooth flour. Tip the entire contents, including the finer particles, into a large bowl. Add the all-purpose flour, baking powder, ground ginger, cinnamon and salt. Mix the dry ingredients thoroughly.

Put all the butter in a saucepan, add the brown sugar and the weighed amounts of golden syrup and black treacle. Warm over a low heat for about 5 minutes, stirring gently, until the butter melts and the mixture is smooth and fluid. Do not bring it to the boil. Remove the pan from the heat and leave the mixture to cool until it is no longer hot.

While the mixture in the saucepan cools, use a fork to beat all the weighed whole eggs with all the milk in a separate bowl. Combine the whites and yolks without whisking them into a foam. Before mixing further, check that the butter and syrup mixture is only lukewarm so it will not cook the eggs.

Pour the lukewarm butter and syrup mixture into the dry ingredients, scraping the saucepan with a spatula. Add the eggs and milk and stir just until combined, with no dry pockets of flour. The batter should be fairly fluid, with noticeable oat particles. Transfer all the batter to the prepared tin and level the surface.

Put the tin on the middle shelf of the oven and bake for about 50–60 minutes at 160°C. The top should be set and dark brown, and the center springy when pressed lightly. A skewer inserted in the center may carry a few moist crumbs, but no raw, liquid batter. If needed, bake for a few more minutes, taking care not to dry out the cake.

Take out the tin and leave the cake in it for about 20 minutes. Then carefully lift the cake by the overhanging paper, transfer it to a wire rack and pull the paper away from the sides. Cool for about another 100 minutes, until the cake is completely cold. Do not seal warm parkin in an airtight wrapping.

Once completely cold, wrap the parkin tightly in baking paper and put it in a container with a lid. Leave for at least 24 hours in a cool place at room temperature so the crumb softens and develops a sticky texture. Only then cut it into 12 pieces. Serve without extra ingredients and keep any remaining pieces tightly sealed in a cool place.