Assemble the cake by spreading a small spoonful of buttercream in the middle of a cake board and place the first cake on top.
Spread a thick layer of buttercream on top of the cake.
Place the second cake upside down, on top of the first cake. By turning the cake upside down, you get a nice flat top.
Cover the cake with a very thin layer of buttercream (crumb coat).
Place the cake in the fridge for at least half an hour to chill.
Cover the cake with another layer of buttercream, setting aside some for piping on top and around the base later.
Smooth the edges with an angled palette knife or straight edged cake scraper.
Place the cake on a cake turntable, sat inside a large baking tray. This will make cleaning up easier later.
Take a handful of sprinkles and brush them against the side of the cake in an upwards motion using your hand. Repeat this all around the cake.
Pour sprinkles on top of the cake and spread them evenly using your hand.
Fill in any gaps with sprinkles using the same techniques.
With your remaining buttercream, pipe a border around the bottom of the cake and some swirls on top. We used Wilton piping nozzles #32 and #2D.