Have ready a greased and lined 18 cm x 28 cm rectangular baking tin and preheat the oven to 160 °C fan, 180 °C conventional, gas mark 4.

Put the butter and caster sugar into a bowl and whisk together until light and fluffy. Gradually whisk in the eggs. Add the flour, baking powder and Flake Pieces and fold in gently until thoroughly combined. Spoon the mixture into the baking tray and smooth the surface.

Dot the sponge mixture randomly with the raspberry halves and then immediately bake for 22-25 minutes or until well risen and firm.

Allow to cool before cutting into portions.