Preheat oven to 350F. Butter and line the base of a loaf tin with parchment paper. Using an electric whisk, beat together the butter and sugar until light and creamy then beat in the eggs one at a time. Add the lemon zest and vanilla. Now beat in the flour and almond flour until you have a thick batter. The batter should be loose enough that it falls off a wooden spoon, if it’s too thick mix in a splash of milk.

Tip the batter into the tin and smooth over the top. Bake for 55 minutes – 1 hour until a skewer inserted in the middle comes out clean. Remove from the oven then leave to cool for 15 mins then remove from the tin, peel away the paper and leave on a wire rack to cool completely before slicing. The loaf will keep in an airtight container for three days.