Nutrition per serving may change if servings are adjusted.
1/2 cup pure maple syrup, plus 4 teaspoons for topping, divided
3/4 cup nonfat milk
2/3 cup evaporated fat-free milk
2 large eggs
2 large egg yolks
Bring 1/2 cup maple syrup to a boil in a saucepan over high heat. Cook until thickened and reduced to about 1/4 cup, about 4 minutes. Reduce heat to low, pour in fat-free milk and evaporated fat-free milk. Stir until the syrup has blended with the milk. Remove from the heat.
Lightly whisk whole eggs and egg yolks in a mixing bowl until combined. Gradually whisk the hot milk mixture into the eggs. Skim off any foam and pour the mixture into four 6-ounce custard cups or ramekins.
Place the filled custard cups 1 inch apart on a large plate. Microwave, uncovered, on Medium power for 3 minutes; rotate the plate a quarter turn and microwave for 2 minutes more. Check for doneness; custard should be well set 1 inch in from the edge and softly set in the center. Remove any custards as they are done; continue microwaving the remaining custards, checking for doneness every 30 seconds. Transfer to a rack to cool until serving.
Serve the custards warm or chilled, with 1 teaspoon of the remaining maple syrup drizzled over each.
Oven Variation: Preheat oven to 350 °F. Place the filled custard cups in a shallow baking dish and add enough hot water to come two-thirds of the way up the sides of the cups. Bake until a knife inserted in the center of a custard comes out clean, 30 to 40 minutes.