Arrange 8 (4-ounce) ramekins inside a 9 by 13-inch baking pan. Spray ramekins lightly with cooking spray.
In a small saucepan, heat 1/3 cup sugar over medium heat, stirring constantly, until sugar melts and forms a medium-brown caramel, about 7 minutes. Working quickly, transfer 2 teaspoons of the caramel to each of the ramekins, swirling as soon as you spoon in the caramel (it will harden quickly). Set aside.
Preheat oven to 350 degrees F.
Combine milk and evaporated milk in a small saucepan over medium heat until warm. Reduce heat to a low simmer and keep milk warm. Meanwhile, bring about 4 cups water to a boil and keep hot. Whisk together eggs, egg yolks, remaining 1/3 cup of sugar, vanilla, nutmeg and cinnamon. Fold pumpkin into egg mixture. Then fold into evaporated milk. Divide filling among ramekins, then place baking sheet in oven. Pour hot water into baking pan until it reaches halfway up the sides of the ramekins. Bake for 35 to 40 minutes, or until flan is just set. Let cool. Place a dessert plate on top of each ramekin and invert; flan should slide out, and syrup should flow onto sides of the dish.