In a small skillet or saucepan cook shallots in margarine or butter until tender. Set aside.
Using 1/2 teaspoon shortening for each cup, grease the bottom and sides of six 6-ounce custard cups or the cups of a popover pan. Or, lightly coat cups with nonstick cooking spray. Place the custard cups on a 15x10x1-inch baking pan; set aside.
In a mixing bowl combine beaten eggs, milk, and shallot mixture. Add all-purpose flour, whole wheat flour, and salt. Beat with a rotary beater or wire whisk until the mixture is smooth. Fill the greased cups half full. Bake in a 400 degree F oven about 40 minutes or until very firm.
Immediately after removal from the oven, prick each popover with a fork to let steam escape. If crisper popovers are desired, return popovers to oven for 5 to 10 minutes more or to desired crispness (be sure the oven is turned off). Serve hot. Makes 6 popovers.