Butter and flour four six inch pans. I use cake strips on my pans for a more even baking as well. Preheat oven to 340F
Sift the dry ingredients together in a large bowl.
Beat the wet ingredients together in a medium bowl.
Add the wet to the dry and mix until just combined. Fold in the sprinkles at the very end and mix until just combined.
Divide the mixture evenly into the cake pans
Bake at 340 for about 25-30 minutes or until the centers are springy to the touch.
For the Buttercream
Beat the butter until light and fluffy. Add the confectioners' sugar and cream and mix. Divide into two batches and dye one with the blue and yellow food coloring.
For the Italian Buttercream
Beat the egg whites and 1/3 cup of sugar until soft peaks form.
In a medium saucepan add the remaining sugar and 1/3 cup water then place on low heat.
Stir constantly until sugar melts and becomes clear. Maintain at medium high heat until temperature reads 235-240F.
Drizzle the sugar into the mixer immediately. Run mixer until meringue is body temperature.
Add room temperature butter into running mixer one piece at a time. Beat until butter is combined and mixture has reached a silky consistency.
Divide into two batches, one small for the dollops and a large one to be dyed blue.
For the Assembly
Use the regular buttercream and pipe the blue and white buttercream between each layer. You can get a two-tone effect by filling one bag with white buttercream, one with the blue and then placing both in a third bag.
Cover the cake with a thin crumb coat and chill for a few minutes.
Cover the cake with the Italian buttercream and smooth with an offset spatula. Lightly press confetti sprinkles on the bottom of the cake and then pipe the white Italian buttercream using an 869 tip.
Video
Notes
If you’re not using 6-inch pans, double the recipe for 8-inch pans or triple the recipe for 9-inch pans.
If you see little clumps of butter after you mix the wet ingredients don’t panic, it all works out by the time you mix in the dry ingredients. You can even use melted butter and warm the milk and sour cream up a bit if you like.
To get FLAT layers that are moist inside and out try using cake strips! You can buy a set online or make your own from foil and paper towels at home. I made a whole blog post on it so check it out if you’re interested!
To pipe the two-tone frosting you fill one bag (1/2 way full) with white frosting, one bag with blue frosting and then put both bags in a third piping bag. No need for a tip, just snip about an inch off each bag.