Preheat the oven to 180C (350F). Mist three 20cm /8inch cake tins with cake release and line the bases with baking parchment.
Put the flour, sugar, baking powder, soda bicarb. in a large mixing bowl. Add the eggs, milk, vanilla extract and butter or margarine.
Start beating at lowest speed setting until ingredients come together. Increase the speed to maximum and beat until the batter is completely smooth - about 30 seconds to one minute.
Fold in the sprinkles, if using, for a Funfetti cake.
Divide between the prepared cake pans and bake 25-28 minutes or until the cakes are golden and feels springy to the touch. A skewer or knife inserted in the centre should come out clean – if not cook for a further 5 minutes.
Leave the cakes to cool for five minutes then carefully turn out on a wire rack to cool.
Make the frosting
Combine all the frosting ingredients and beat together, on lowest speed setting initially, then increase to maximum speed until frosting holds peaks.
Assemble the cake
Level the cake layers, if needed. Sandwich together with a thin layer of frosting and smooth frosting over top and sides.
Tint remaining buttercream with the colour of your choice (or leave it white) and then pipe over top of the cake to decorate.
Add plenty of sprinkles and serve!
Unless specified otherwise all your ingredients including butter eggs and milk should be at room temperature in order to achieve a smooth batter. If one or more of the ingredients are cold they will cause your batter to split or look curdled.
If your milk is cold from the fridge then heat briefly in the microwave or saucepan until just tepid. Make sure the milk is body temperature - not too hot!
Place cold eggs into warm water for five minutes to bring them back to room temperature.
Cut cold butter into cubes and leave for an hour on your counter to warm up or use margarine.
How do I know if my cake is done?
Oven temperatures can vary so set a timer for 5 minutes before the specified time. The cake is done when the top is springy to the touch, the cake has just started to pull away from the edge of the tin and a skewer or toothpick inserted in the centre comes out clean or with a few moist crumbs.
Avoid opening the oven too often – or too early! - to check if the cake is done or your oven will start losing heat.