Preheat oven to 325°F.
Butter a 2-quart casserole, and place it in a baking pan that will hold it with room on all sides.
Cream butter in a large bowl.
Blend in the following ingredients in the order given: honey, egg yolks, lemon juice, lemon rind, milk, flour, Grapenuts. (Mixture may look curdled.) In a medium-size bowl, beat egg whites until stiff, and then fold into pudding mixture.
Spoon pudding into prepared casserole, and sprinkle with nutmeg.
Place on middle shelf of oven, and fill baking pan with enough hot water to almost reach top of casserole.
Bake for 1 hour, or until top springs back when lightly touched.
This pudding makes its own sauce.