½ cup sugar in the raw or coarse sugar for the top of the custard
Preheat oven to 300 degrees.
In a medium saucepan, heat cream, milk, cinnamon stick, nutmeg, and ginger over medium heat, simmering to infuse flavors. Let stand for 15 minutes; remove cinnamon stick.
In a large bowl, whisk egg yolks and granulated sugar together. Whisking constantly, gradually add hot cream mixture, followed by pumpkin purée.
Divide mixture among 4 ovenproof ramekins and place in a hot water bath. Place on the center rack of preheated oven and cook for 30−45 minutes—custard should be almost set but slightly jiggly in the center. Remove ramekins from water bath and cool for 20 minutes.
Tightly wrap each ramekin with plastic, being careful not to touch custard with the wrap, and refrigerate overnight.
To serve, unwrap custards and place a thin, even layer of sugar on top of each. Caramelize sugar with a blowtorch. Let stand for 1 minute and serve.