Heat oven to 325 degrees F. Place eight 6-ounce custard cups nearby so theyll be within easy reach.
Heat granulated sugar in medium-size heavy skillet or saucepan over medium heat until sugar melts and caramelizes to a golden amber color. Watch very carefully so sugar doesnt become too dark; it will change color quickly.
Spoon caramel into custard cups, tilting to coat bottoms and 1 inch up sides; work quickly while caramel is still pourable. Place in large roasting pan.
Whisk brown sugar, pumpkin, eggs, milk, vanilla and allspice in large bowl. Divide equally among custard cups. Pour enough simmering water into roasting pan to come halfway up sides of cups.
Bake in 325 degree F oven for 50 minutes or until knife inserted in centers comes out clean. Carefully remove cups from water to wire rack. Cool slightly. Refrigerate cups overnight.
To serve, run a small spatula around edge of each cup. Invert flans onto 8 serving dishes, shaking to release flans. Scrape any remaining caramel from cups onto top of each flan. Makes 8 servings.