Step 1

Preheat oven to 350F. Grease and flour two 8" cake rounds and line with parchment.

Step 2

In a medium bowl, whisk flour, baking powder, and salt until well combined. Set aside.

Step 3

Using a stand mixer fitted with a paddle attachment, cream the butter and sugar on med-high until pale and fluffy (about 3mins). Reduce speed and add eggs one at a time fully incorporating after each addition. Add vanilla.

Step 4

Alternate adding flour mixture and buttermilk, beginning and ending with flour (3 additions of flour and 2 of milk). Fully incorporating after each addition.

Step 5

Bake for 30-35mins or until a toothpick inserted into the center comes out mostly clean.

Step 6

Place cakes on wire rack to cool for 10mins then turn out onto wire rack.

Step 7

Place egg whites and sugar into the bowl of a stand mixer, whisk until combined.*

Step 8

Place bowl over a pot with 1-2" of simmering water and whisk constantly until the mixture is hot and no longer grainy to the touch or reads 160F on a candy thermometer (approx. 3mins)

Step 9

Place bowl on your stand mixer and whisk on med-high until the meringue is stiff and cooled (the bowl is no longer warm to the touch (approx. 5-10mins)).

Step 10

Switch to paddle attachment. Slowly add cubed butter and mix until smooth.**

Step 11

Add vanilla and whip until smooth.

Step 12

Place one layer of cake on a cake stand or serving plate. Top with approximately 1 cup of buttercream. Repeat with remaining layer and crumb coat the cake. Chill for 20mins.

Step 13

Frost the top and sides of the cake and smooth with a bench scraper.

Step 14

If desired, use a decorating comb to give texture to the sides.***

Step 15

Mix confetti and nonpareils in a small bowl. Press sprinkles gently along the bottom of the cake and sprinkle along the top. For the speckled sides, I grabbed a pinch of sprinkles and tossed them randomly at the sides.

Step 16

Pipe rosettes using a 1M tip with remainder of frosting.