Cake: Preheat the oven to 180 degrees C. Line the base and sides of a 23 x 13 x 7cm loaf tin with baking paper.
Beat together softened butter and caster sugar with an electric hand mixer until well combined. Beat in eggs, 120g marmalade and orange zest. Using a large spoon, fold in flour, baking powder and ground almonds until there is no sign of any flour.
Spoon the cake mixture into the loaf tin. Bake for 40-45 minutes or until a skewer inserted into the centre of the cake comes out clean. Cool in the tin for 5 minutes.
Glaze: Gently warm 2 or 3 tablespoons of coarse-cut marmalade in a non-stick pan, then spoon over the top of the cake while it is still warm. Remove the cake from the tin, and leave to cool completely on a wire rack.