This American-style chocolate traybake is super-easy, can be prepared in advance and cuts into even portions. It's perfect for birthday parties or bake sales

• Preparation and cooking time
  • Prep:15 mins
  • Cook:30 mins
• Easy
• Serves 10

• Freezable (un-iced only)
• Vegetarian

Ingredients

For the chocolate sponge

• 185ml vegetable oil, plus extra for the tin
• 250g plain flour
• 80g cocoa powder
• 2½ tsp baking powder
• 1 tsp bicarbonate of soda
• 325g light brown soft sugar
• 250ml buttermilk
• 125ml strong coffee or espresso, (can be warm, but not hot)
• 2 tsp vanilla extract
• 2 large eggs

For the icing

• 150g salted butter, softened
• 200g icing sugar
• 4 tbsp cocoa powder
• 2 tbsp milk
• sprinkles, sweets, chocolate shavings or nuts, to decorate

Method

• STEP 1

  Heat oven to 180C/160C fan/gas 4. Oil and line the base and sides of a 33cm x 23cm roasting tin or cake tin with a lip of at least 2½ cm. Combine the flour, cocoa powder, baking powder, bicarb, sugar and a good pinch of salt in a large bowl. Rub any lumps of sugar between your fingers, shaking the bowl a few times to bring them to the surface.

• STEP 2

  Whisk the oil, buttermilk, coffee, vanilla and eggs in a jug, then pour the wet ingredients into the dry. Use a spatula to stir well, removing any pockets of flour. Pour the mixture into the lined tin and bake for 25-30 mins until a skewer inserted into the centre comes out clean. If any wet cake mixture clings to the skewer, return the cake to the oven for 5 mins, then check again. Once cooked, remove from the oven and leave to cool in the tin for at least 20 mins.

• STEP 3

  Meanwhile, make the icing. Melt the butter in a saucepan, then remove from the heat and stir in the icing sugar, cocoa powder and milk. The icing will be very runny but will thicken a little as it cools. (If the icing has set too much before the cake has cooled, reheat it slightly to make it easier to pour.)

• STEP 4

  Pour the icing over the cake and leave to set. Decorate with the sweets, sprinkles, chocolate shavings or nuts, then cut into squares and dig in.