In a large heavy saucepan, combine the sugar, cornstarch and lemon juice until smooth. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat to low; cook and stir for 2 minutes longer. Remove from the heat. Stir a small amount of hot filling into egg yolks; return all to the pan, stirring constantly. Bring to a gentle boil; cook and stir for 2 minutes. Remove from the heat; gently stir in butter and lemon peel until blended. Pour into a large bowl; cover surface with plastic wrap. Cover and refrigerate until serving.
In a large bowl, combine the flour, sugar, baking powder, ginger, cinnamon, salt and cloves. In another bowl, combine the egg, milk, oil and molasses until smooth; stir into dry ingredients just until moistened.
Fill paper-lined muffin cups half full. Bake at 375° for 15-20 minutes or until a toothpick inserted near the center comes out clean. Cool for 5 minutes before removing from pan to a wire rack. Serve warm with lemon curd. Yield: 1 dozen (1 cup lemon curd).