Preheat oven to 350°F with rack in the center of the oven.

Use the extra butter to grease 2 8-inch cake tins. Line the bottom with a circle of parchment paper.

Beat the eggs and sugar for 2 minutes until light in color and doubled in volume. Set aside.

Add the butter to the eggs while beating, and then add the vanilla.

Sift the flour and baking powder into the batter and beat on low, just in until well mixed and there are no lumps. Do not overbeat.

Divide the batter evenly between the 2 cake pans and smooth the tops. Bake for 25 minutes until golden brown and the cake should spring back when pressed lightly. When a toothpick inserted in the center it should come out clean.

Turn off the oven, open the door slightly and allow to cool in the oven for 15 minutes to cool down slowly and prevent deflating.

Remove from the oven and allow to cool in the pan for 10 more minutes.

After 10 minutes, run a knife around the edge and turn out onto a cooling rack to cool completely.

While the cakes are cooling, prepare the filling.

Whip the cream until stiff.

Turn both cakes with the flat tops facing you. Spread the cream on one side and jam on the other.

Sandwich the 2 cakes together and dust lightly with powdered sugar.