Get the party started with this fun and colorful rainbow sprinkle cake. White sour cream cake layers hold a flurry of funfetti inside.There's no need to use fancy sprinkles for the inside of this cake. Look for ice cream sprinkles, called 'jimmies' in the ice cream toppings section at the grocery store. They won't melt with moisture, but under the oven's heat, they melt just right to leave colorful speckles throughout the cake layers.
8round gourmet lollipopssee blog post for shopping link
Instructions
Sprinkle cake layers
Preheat the oven to 350F.
In the bowl of an electric mixer fitted with the whip attachment, beat the butter until creamy. Sprinkle in the granulated sugar gradually as you mix. Beat until light and fluffy.
In a separate large mixing bowl, sift together the flour, baking soda, baking powder, and salt.
In a 4-cup measure or batter bowl with a pour spout, whisk together the egg whites, vanilla, sour cream, and milk.
Switch the mixer beater to the paddle attachment Beat 1/3 of the dry ingredients into the creamed butter mixture until just incorporated. Add in half of the liquid mixture; beat until combined. Continue adding 1/3 flour mixture followed by the remaining liquid; end with the flour mixture. Beat until the mixture is lightened in color and fluffy, about 2 minutes. Fold in the rainbow sprinkles.
Coat three 8-inch cake pans with flour-based baking spray. Alternatively, grease and flour the pans.
Divide the cake batter between the prepared pans. Smooth the top of the batter with the flat edge of the offset spatula.
Bake the cakes for 25-30 minutes, or until the cakes spring back when pressed in the centers. Remove the cakes from the oven. If the tops are slightly rounded, flatten gently using a paper towel while the cakes are still warm. Do this gently and carefully as steam will escape as you press.
Remove cakes to a wire rack to cool completely.
Buttercream
Beat the butter in the bowl of an electric mixer fitted with the whip attachment. Whip until creamy. Add the confectioners’ sugar. Beat until combined. Add vanilla extract; mix well. Beat on medium speed adding milk or cream 1 tablespoon at a time, until the mixture thins to piping consistency. Beat on high speed until the frosting turns almost white in color, about 4 minutes with a timer set. Scrape down the bowl. Beat again on high speed. Remove 2/3 cup of frosting to a piping bag fitted with a large open star tip (also called French pastry tube).
Fill two of the cooled cake layers with about 1/2 cup of the buttercream on each layer. Spread evenly. Stack them and then place the remaining cake layer on top. Generously cover the cake with the remaining buttercream using an offset spatula. Immediately coat the sides of the cake with sprinkles. To do this, place the cake on a baking sheet. Pick up handfuls of sprinkles and press them on from the bottom edge of the cake to the top. Repeat until the entire cake is coated Refrigerate the cake until the frosting firms.
Using the reserved piping bag of frosting, pipe 8 large swirls on the top edge of the cake, well-spaced. Immediately top with sprinkles.
Just before serving add a lollipop between each swirl on top of the cake with their sticks meeting at the top center of the cake.
Serve this cake at room temperature. The cake's texture and flavors are completely developed at room temperature.
Notes
What to expect: Moist cake layers with a light sour cream tang and lots of beautiful rainbow sprinkles inside. White cakes are notorious for drying out quickly, so be sure to keep this cake covered. Decor: Top the cake with the lollipops just before serving. If you have leftovers, remove the lollipops from the cake before refrigerating. If left on the cake for more than 6 hours, the lollipops will begin to melt with the moisture from the cake.White Cake Flavor: I use Bakto White Cake Flavor (extract) in this cake, which gives it that old school bakery flavor. (See blog post for link.) It reminds me a little of Princess Cake emulsion, but not as strong, as it is a natural flavoring, and not an artificial product. It has vanilla flavor with small background notes of almond and something a little floral. If you don't have White Cake Flavor in your cabinet, use 1 teaspoon of vanilla extract and 1/4 teaspoon almond extract for a close approximation. Or, if you're strictly a vanilla lover, just use vanilla extract.
Keyword american buttercream, rainbow sprinkles, sour cream cake layers, white buttercream, white cake flavor