This cake is so simple and so cute—the perfect way to show mom a little love when she's having one of those days. Use equal amounts of eggs, butter, flour and sugar. Using an electric mixer, beat the eggs and sugar at length until the mixture has thickened and become pale yellow in color. Add the melted butter, then the flour and the melted chocolate. Pour the batter into a heart-shaped baking pan, and bake at 350° F for 30 to 40 minutes.