Pre-heat oven to 180C/350F degrees
Line a 8-inch square baking tin with parchment paper. Divide the tin into two by placing a thick layer of aluminum foil down the center.
Whisk the butter until creamy
Add the low carb sweetener and continue to whisk
Whisk in the egg yolks, one at time,
Add the vanilla extract.
Whisk in the coconut flour, salt and baking powder.
In a separate bowl whisk the egg whites to stiff peaks.
Gently fold in the egg whites and mix until combined.
Spoon half of the mixture into another bowl and stir in the red food colouring. Adjust the colouring until you have a pink colour.
Spoon into the tin, evenly smooth out the cake mixture.
Bake for 25 minutes until the sponge is golden and firm.
Remove from the oven and cool.