Chocolate Triangle Cake

This chocolate cake is more architecture project than dessert. Two thin sheet cakes get cut into seven progressively narrower strips (from 3 ½ inches down to ½ inch), spread with chocolate frosting, then stacked into a slanted pyramid that becomes a triangle when laid on its side. Cut crosswise, each slice reveals dramatic vertical chocolate stripes between thin layers of pale sponge.

The cake itself is a basic separated-egg sponge: yolks beaten with sugar until pale and thick, whites whipped to stiff peaks, then folded together with flour and baking powder. Five minutes at high heat is all the bake needs. The thin layers cook fast and would dry out at lower temperatures.

Line the jellyroll pans with greased and floured waxed paper. Cake this thin will tear if pulled out of an unprotected pan, and tearing ruins the precision strips you’ll need for clean stacking.

The weighting step is essential. After stacking the strips into two slanted stacks, cover with foil and weight them down for an hour. This compresses the layers, helps the frosting set as glue between them, and gives you the dense, tight crumb that makes the triangle slice cleanly.

Chef Tips

• A long serrated knife makes the cleanest strip cuts. Drag, don’t press.
• Stiff peaks for the egg whites means they hold their shape when the beater is lifted, but still bend slightly at the tip. Over-beaten whites turn dry and refuse to fold smoothly.
• Fold gently with a rubber spatula. Aggressive folding deflates the whites and yields a flat, dense cake.
• Use a quality satiny chocolate frosting. Stiffer frostings won’t spread thinly between fragile cake layers without tearing them.

Variations

• Coat the assembled triangle with extra chocolate frosting or ganache before slicing for an all-chocolate exterior.
• Add a tablespoon of espresso powder to the frosting for a mocha version.
• Sprinkle the assembled cake with chopped toasted hazelnuts or shaved chocolate for added texture and visual drama.