Preheat oven to 350°. In a small saucepan, heat milk to just below boiling, bubbles will form all over the surface (scalded milk is heated to 180 to 185º). In a medium bowl, lightly beat eggs with a wire whisk. Add pumpkin, brown sugar, butter, spice, and vanilla. Mix until well blended. Gradually whisk in hot milk. Mix well until all ingredients are combined. Evenly divide pumpkin mixture among 12 (6-ounce) custard cups. Place cups in two 9 by 13 inch baking pans. Place pans on oven rack and add hot tap water to the pans until the water is halfway up sides of cups. Bake 35-40 minutes. Check after 35 minutes. Custard centers should be slightly wobbly. Remove custard from oven and allow to cool in water bath. Cover with plastic wrap and refrigerate. Just before serving, preheat oven broiler. Sprinkle 2 teaspoons sugar on each custard. Arrange on a baking sheet and place under hot broiler. Broil until sugar melts and bubbles. Watch closely to prevent burning. Sugar should be lightly brown and caramelized. Or hold a propane kitchen torch (also called a salamander) about 2-inches from custard tops to caramelize sugar. Serve at once. Refrigerate leftovers for up to 5 days.