Triangles

Sandwich together four or five layers of ¼-inch (6 mm) thick sponge (such as Swiss roll sponge or seven-layer sponge) with buttercream in a contrasting color. Press the layers together firmly. Chill to solidify the cream. Cut the cake into strips 2 to 2½ inches (5 to 6 cm) wide.

Place a strip at the edge of the bench and, using a sharp knife, cut diagonally into triangles (a). Turn the triangles so the layers are vertical (b). Attach them back to back with a layer of buttercream to form a larger triangle (c).