For the batter and a 24 cm-in-diameter springform pan: 320 g of all-purpose flour 90 g of cocoa powder 250 g of sugar 150 g of butter 150 g of sour cream 2 large eggs 230 ml of milk 1 tsp of . Heat oven to 180C/160C fan/gas 4 and line baking trays with parchment. Mix flour, cocoa, bicarb, sugar and a pinch of salt. Whisk the egg, oil and buttermilk together, then mix into dry ingredients with 75ml boiling water.. Bake in the preheated oven for 10 to 12 minutes. Let cakes cool then make sandwiches from two cakes filled with the filling. To Make Whoopie Pie Filling: Beat egg white and mix with the milk, 1 teaspoon vanilla and 125g of the icing sugar. Mix well then beat in the butter and the remaining sugar. Beat until light and fluffy. Pumpkin. To cook the pumpkin, either bake or steam it, then peel and . Preheat oven to 180 C / Gas 4. Grease baking trays. Sift together the 250g flour, bicarbonate of soda,1/4 teaspoon salt, cocoa and 200g sugar.. While the mini pie halves are baking, prepare the filling by beating the butter in a bowl until pale and creamy. Add the vanilla extract and gradually add the icing sugar until the mixture is light and fluffy.. Spoon 12 even dollops onto each baking sheet, leaving plenty of space between them. Bake on the middle shelf of the oven for 10 to 12 minutes. Bake on the middle shelf of the oven for 10 to 12 minutes..