1. Preheat oven to 300°.

2. Remove stems from pumpkins and cut off tops. Hollow out pumpkins, discarding seeds, reserving pulp, and leaving ¼-inch perimeter of pulp in shells.

3. Cut pumpkin pulp into cubes and place in a saucepan. Cover with water and bring to a boil. Cook until pumpkin is tender, about 20 to 30 minutes. Drain pumpkin and place in a food processor. Purée until very fine, and strain. Reserve ¾ cup pumpkin pulp for this recipe and refrigerate remainder of pulp for another use.

4. Combine milk, cream, 2 tablespoons sugar, cinnamon, nutmeg, and vanilla bean in a saucepan. Bring to a boil, stirring occasionally. Remove from heat just after mixture has come to a boil. Remove vanilla bean and add pumpkin purée. Stir until ingredients are combined and allow mixture to cool.

5. Combine 2 tablespoons sugar and egg yolks and beat until eggs are pale and form a light ribbon. Add a third of milk-pumpkin mixture to egg-yolk mixture and beat to combine. Return ingredients to saucepan and cook over very low heat, stirring, for 2 minutes. Be careful not to let mixture come to a simmer.

6. Beat the sauce for 1 minute, off heat, to cool, and strain through a fine sieve.

7. Spoon custard mixture into pumpkin shells. Place shells on a baking sheet and bake for 45 minutes to 1 hour, or until custard has set. Remove from oven and allow to cool on baking sheet.

8. Preheat broiler.

9. Combine white sugar and brown sugar and mix. Spoon sugar mixture over Custards. Place pumpkin shells under broiler and broil until sugar has caramelized. Check broiler after 2 minutes and turn pumpkin shells if sugar appears to be browning only in one spot.

To Serve: Place pumpkin shells on six dessert plates. Place a scoop of Spice Ice Cream on top of each pumpkin. Garnish with Pumpkin Chips.