Homemade purée, optional, to prepare ahead: Cut a red kuri or butternut squash in half, remove the seeds, place the halves cut-side down on a baking sheet, and bake for 45 to 60 minutes at 180°C (350°F), until a knife slides in without resistance. Scoop out the flesh, blend it, then let it drain in a fine-mesh sieve for 30 minutes. Allow about 2.6 lb (1.2 kg) whole squash for the 15 oz (425 g) of purée in the recipe. It should be thick like applesauce and not release any water.
425 g plain pumpkin purée,
Preheat the oven to 230°C.
Whisk together the sugar, cornstarch, salt, cinnamon, ginger, and nutmeg.