1. Preheat oven to 325°F (160°C). Combine cream, milk, sugar, ginger, cinnamon, allspice and salt in medium saucepan. Bring to simmer over medium heat. Meanwhile, in large bowl, whisk yolks to blend with maple syrup. Slowly pour hot cream mixture into egg yolk mixture, whisking constantly. Whisk in sweet potato and vanilla.
Place ten 1/2-cup (4-oz) ramekins into a large roasting pan lined with a clean kitchen towel (to prevent ramekins from sliding). Fill each ramekin with scant 1/2 cup (125 mL) custard mixture.
Set roasting pan on middle rack of oven. Carefully pour hot water into the roasting pan to come halfway up sides of ramekins (be careful not to splash water into ramekins). Bake 30 min., or until edges of custards are set but centre jiggles slightly. Remove roasting pan from oven. Let custards stand in water bath 5 min. before removing ramekins from water bath. Cool 30 min. at room temperature then cover with plastic wrap; chill 2 hr. or until cold. Store in fridge up to 2 days before serving.
Sprinkle custards with crumbled gingersnaps just before serving.
Turn into crème brûlée by sprinkling tops with sugar and broiling 2 to 3 min. until sugar begins to brown. Let sugar coating cool and harden before serving.
Cook sweet potato in microwave by piercing several times with a fork. Microwave on HIGH 8 to 10 min. or until fork tender.