Preheat the oven to 180°C.

Grease and line a 23cm square shallow cake tin.

Sift the flour and baking powder into a large bowl.

Add the butter, sugar, eggs and vanilla extract. Using an electric hand whisk, beat until the mixture is very smooth and creamy. Fold in the chocolate chips.

Spoon the mixture into the cake tin and gently smooth the surface. Bake in the oven for 40-45 minutes.

Leave the cake to cool in the tin for 5 minutes, then turn out onto a wire rack to cool completely.