White Chocolate Frosted White Cake

White chocolate shows up twice in this cake, once melted into a tender buttermilk batter and again in the frosting, which makes it a genuine treat for white-chocolate lovers rather than just a white cake by color.

The frosting is the quiet showstopper. It starts with a cooked base, white chocolate, flour, and milk simmered until very thick, an old-fashioned technique sometimes called ermine or boiled-milk frosting. Once it’s completely cool, you beat it into creamed butter and sugar until it turns light and billowy, like whipped cream. The payoff is a frosting that’s silky and far less cloying than a standard buttercream.

A couple of cautions. Melt the white chocolate gently, since it scorches more easily than dark, and make sure that cooked frosting base is fully cooled before it meets the butter, or the whole thing will melt and separate instead of whipping up fluffy.

Pro Tips

• Melt the white chocolate slowly over low heat; it burns and seizes more easily than dark chocolate.
• Cool the cooked frosting base completely before beating it into the butter, or the frosting will separate.
• Don’t overbake; pull the layers when a toothpick comes out clean to keep the crumb moist.

Variations

• Add fresh raspberries or a raspberry filling between the layers to cut the sweetness.
• Fold lemon or almond extract into the batter for a different flavor note.
• Finish with white chocolate curls or shavings over the frosted cake.