Place ten 8-ounce oven-proof ramekins in bottom of large deep roasting pan. Set aside.
Preheat oven to 350°F.
In a small heavy bottomed saucepan, add 1 cup sugar and 1/3 cup water. Mix.
Place saucepan over medium high heat.
Heat and mix to dissolve sugar. To prevent crystallization of sugar, use a wet pastry brush to brush down any sugar on the sides of pan.
Cook sugar to an amber brown, brushing down sides of any sugar, and gently swirling pan occasionally.
Remove from heat and, working quickly, pour a thin layer of caramel into ramekins tilting to coat bottoms. Set aside.
In the bowl of an electric mixer fitted with a whisk attachment or a blender on medium speed, combine pumpkin, ginger, cinnamon, nutmeg and 3 cups of milk. Blend until smooth.
Place a large saucepan over medium heat. Add pumpkin mixture, remaining 5 cups milk and remaining 1 1/2 cups sugar. Mix with a whisk to combine. Heat until it comes to a simmer, whisking occasionally. Remove from heat. Set aside.
In the bowl of an electric mixer fitted with a whisk attachment on medium high, whip whole eggs, yolks and vanilla 1 minute.
Reduce to low speed. Temper the eggs by slowly adding 1 cup of hot milk mixture. Repeat with another cup of hot milk mixture.
Remove the bowl from the mixer and add remaining milk mixture, stirring slowly to avoid creating "foam" in the custard.
Using a large measuring cup with a spout or a ladle, fill the prepared ramekins 1/4-inch from the top.
Place the roasting pan in oven. Add enough hot water to reach 1/2-inch from the tops of the ramekins. Cook until the blade of paring knife inserted into center comes out clean, about 1 hour and 20 minutes.
Remove from water bath and cool on a wire rack.
Refrigerate and chill before serving.
To serve, run a paring knife around the edge, invert flans onto rimmed dessert plates to catch the caramel sauce.
Garnish with a dollop of whipped cream sprinkled with cinnamon.