Preheat the oven to 170 degrees Celsius. Cream together the butter and sugar in a freestanding mixture until fully combined and fluffy. Add the eggs one by one and scrape down the sides of the bowl between each addition. Beat for 1-2 minutes until the mixture is smooth.
In another bowl combine the flour, salt and baking powder, and mix until evenly distributed.
Add the flour to the egg mixture in 3 separate parts. In another jug mix together the milk and the vanilla extract, then add to the mixture, beating on a slow speed.
Divide the batter into 3 equal quantities, and colour each batch a different shade of pink using the gel food colouring.
Line 3, 10cm round baking tins and add each batter separately to the three tins. Bake for 20-25 minutes until a skewer inserted into the middle of the cake comes out clean, allow to cool fully on a cooling rack.