1. Prepare the Crust:

1. Preheat oven to 350°F (175°C).
2. In a small saucepan, combine sugar and water. Cook over medium heat, stirring constantly, until sugar dissolves and turns amber in color. Pour caramel into a 9-inch round baking dish, tilting to coat the bottom evenly.
3. In a blender, combine sweetened condensed milk, evaporated milk, pumpkin puree, eggs, vanilla extract, cinnamon, nutmeg, and ginger. Blend until smooth.
4. Pour the pumpkin mixture over the caramel in the baking dish. Place the dish in a larger roasting pan and fill the roasting pan with hot water until it reaches halfway up the sides of the baking dish.
5. Bake for 45-50 minutes, or until a knife inserted in the center comes out clean. Remove from the oven and let cool to room temperature, then refrigerate for at least 4 hours or overnight.
6. To serve, run a knife around the edges of the dish and invert onto a serving plate. The caramel will flow over the flan.