Preheat oven to 325°. In a small heavy saucepan, spread sugar; cook, without stirring, over medium-low heat until it begins to melt. Gently drag melted sugar to center of pan so sugar melts evenly. Cook, without stirring, until melted sugar turns a medium amber color, about 8 minutes. Quickly pour into an ungreased 9-in. deep-dish pie plate, tilting to coat bottom of plate.

In a large saucepan, heat cream until bubbles form around side of pan; remove from heat. In a large bowl, whisk egg yolks, egg, sugar, pumpkin, cinnamon and vanilla until blended. Slowly stir in hot cream. Pour into pie plate.

Place pie plate in a larger baking pan. Place pan on oven rack; add very hot water to pan to within 1/2 in. of top of pie plate. Bake 50-60 minutes or until center is just set (mixture will jiggle). Immediately remove flan from water bath to a wire rack; cool 1 hour. Refrigerate until cold, about 5 hours or overnight.

Run a knife around edge and invert onto a rimmed serving platter. Refrigerate leftovers.