Step 1: Prepare the Cake Tins

• Preheat the oven: Set your oven to 170°C (150°C fan)/325°F/gas mark 3.
• Prepare the tins: Grease and line two 20cm round cake tins with baking parchment.

Step 2: Make the Cake Batter

• Cream the butter and sugar: In a large mixing bowl, beat the softened butter and caster sugar together until light and fluffy using an electric mixer.
• Add the eggs: Beat in the eggs one at a time, ensuring each one is fully incorporated before adding the next. Add the vanilla extract if using.
• Fold in the dry ingredients: Sift the self-raising flour and baking powder into the mixture and gently fold it in using a spatula. Be careful not to overmix the batter.

Step 3: Bake the Sponge

• Divide the batter: Evenly divide the batter between the two prepared tins and smooth the tops.
• Bake: Place the tins in the preheated oven and bake for 20-25 minutes, or until the cakes are golden and springy to the touch. A skewer inserted into the center should come out clean.
• Cool the cakes: Allow the cakes to cool in the tins for 5 minutes before turning them out onto a wire rack to cool completely.

Step 4: Fill and Assemble the Cake

• Spread the filling: Once the cakes have completely cooled, spread one cake with a generous layer of strawberry or raspberry jam. Whip the cream until soft peaks form and spread it over the jam layer.
• Sandwich the cakes: Place the second cake on top of the first to create a sandwich, pressing gently to secure.

Step 5: Decorate and Serve

• Dust with icing sugar: For a classic finish, dust the top of the cake with a light layer of icing sugar before serving.
• Slice and serve: Enjoy the cake with a cup of tea or coffee for a quintessentially British treat.