Put the remaining 150g sugar, the rest of the vanilla and the butter in a bowl, and beat together for 4-5 mins using an electric whisk until lightened in colour and very fluffy. Crack in the eggs, one at a time, beating well after each addition. Beat in half the custard. Once everything is well combined, sprinkle in the ground almonds, flour and baking powder. Fold in using a spatula until no flour remains.
