Angel Cake

Cream of tartar stabilizes egg white foam by lowering pH, which strengthens protein bonds and prevents overbeating. Sifting flour five times aerates it and ensures even distribution when gently folded, preventing deflation of the delicate foam structure. Inverting the cake while cooling prevents collapse—the egg protein matrix is still setting as it cools, and gravity would compress the fragile structure if left upright. The ungreased pan is critical: the batter needs to cling to the sides as it rises and sets, creating the characteristic tall, tender texture.