For the Cake Layers:
For the Swiss Meringue Buttercream:
Add egg whites and sugar, and simmer over a pot of water (not boiling), whisking constantly, until temperature reaches 140°F, or if you don't have a candy thermometer, until the sugar has completely dissolved and the egg whites are hot.
With whisk attachment of mixer, begin to whip until the mixture is thick, glossy, and cool. Switch over to paddle attachment and, while mixing on medium speed, gradually add softened butter in chunks until incorporated, and mix until it has reached a silky smooth texture (if curdles, keep mixing and it will come back to smooth).
*If doing the ruffly cake, you can increase the cake recipe by 50% for a 3-layer cake (or 6, if you slice each in 2) and make the buttercream x 3. It requires tons and tons of buttercream. Trust me!
**This cake is sturdy enough to be used under fondant, stacked, etc. but also moist and tasty enough too go on its own with almost any type of frosting, glaze, etc.
For the Cake:
For the Swiss Meringue Buttercream