Place a small dollop of frosting on the cake platter or plate before putting the first layer down. This will stick the cake to the plate.
Add the first layer then frost the top of it, then add the remaining layers and frost. Thinly crumb coat the edges and top, then return to the freezer for about 20 minutes to set the frosting.
Once the frosting has set, finish the sides and top with either swooping motions for a creamy look, or use a cake edge to get a straight side.
Once the exterior frosting is to your liking, mix the 1 tbsp. of cocoa powder with a tiny trickle of water. Lightly dip your basting brush (or clean paintbrush) in the mixture and then flick the brown mixture lightly all over the cake. Repeat until it's as speckled as you'd like it.
Top with Cadbury Mini Eggs and enjoy!