Run a long, sharp knife around the edge of the cake and invert it onto a rack, then invert it again onto another rack so that the cake is right side up. Place the cake on a serving platter and serve. Or freeze it, wrapped in foil, for up to 6 months. Thaw the cake overnight on the counter before serving. Both fresh lemon juice and lemon zest work wonders in transforming an ordinary white cake mix into this exceptional, lemony cake.
Buttermilk adds flavor as well, plus a moist texture.