In a large mixing bowl, cream together the softened butter until pale and fluffy.
Mix in the eggs and vanilla extract and beat together.
In stages fold in the flour until it’s fully combined. You can add a tbsp of milk if the mixture is a little too thick.
Pour evenly into two greased 20cm sandwich tins, and place in a pre-heated oven at 180c / 160c fan for approx. 35 minutes, or until the sponge is baked, testing with a skewer. Once cooked, remove from the oven and allow to cool for a few minutes before turning out onto a wire rack to cool fully.
For the icing, combine the Mascarpone, icing sugar and vanilla in a large bowl and beat together.
To assemble the cake, spread a thick layer of the icing on one half of the cooled sponge, and a layer of jam on the other. Sandwich the two coated layers of the cake together, and finish with a dusting of icing sugar.