Preheat oven to 180˚C. Grease the base and sides of a 7cm deep, 11cm x 21cm loaf pan. Line with baking paper, allowing a 2cm overhang at both long ends.
Cream butter and sugar until pale in an electric mixer. Add beaten eggs in two portions, beating mixture well after each addition.
Stir in mashed banana.
Sift flour with baking powder (and Bake Aid if not adding to Milk) over the banana mixture.
Stir Biohawk product of choice into milk and then stir into the mixture with a wooden spoon until well combined.
Spoon half the mixture into loaf pan. Spread the raspberries over the surface and add the second half of the mixture. Smooth surface.
Bake for 45-50 minutes (testing with skewer). Cool in pan for 10 minutes. Cool completely on wire rack.
Note: Can be cut into 10 even slices and stored in freezer in a sealable plastic container with slices separated with baking paper.