Preheat the oven to 180°C (350°F). Grease and line 8-inch spherical cake tins with parchment paper.

Cream the butter and sugar together in a large bowl until light and fluffy using an electric hand mixer or stand mixer.

Add the eggs one at a time, beating well after each addition. Then mix in the vanilla extract.

Sift the flour and baking powder into the bowl and gently fold them into the wet mixture with a spatula. Add the milk to loosen the batter, if necessary.

Divide the batter equally between the two prepared tins, smoothing the tops with the back of a spoon.

Bake in the preheated oven for 25-30 minutes, or until a skewer inserted into the center comes out clean.

Cool the cakes in the tins for 10 minutes before transferring them to a wire rack to cool completely.

Prepare the buttercream filling by beating the softened butter and icing sugar together until smooth and creamy.

Assemble the cake: Once the cakes are completely cool, spread the jam on the top of one of the cakes, then spread the buttercream on top of the jam. Carefully place the second cake on top to create a sandwich.

Dust with icing sugar for a classic finish, and garnish with fresh strawberries if desired.