1. Prepare the pumpkin puree: Preheat oven to 425 degrees Fahrenheit. Cut pumpkins into quarters and scoop out seeds. Drizzle with oil and season with salt. Place pumpkins, cut side down, on sheet. Roast, turning pumpkins occasionally, about 45 minutes. Let cool. With the back of a spoon scrape out flesh. Use only the smooth part and leave behind the stringy parts that may be found in center of some pumpkins (next to where the seeds were).
2. In a medium saucepan, combine sugar, cornstarch, salt, and soy milk. Cook over medium heat, stirring continuously, until mixture boils and thickens. Reduce heat and simmer, stirring continuously, for two minutes. Remove from heat.
3. Beat egg until foamy. To prevent the egg from cooking, gradually stir in about half cup of the hot milk mixture. Pour the egg mixture back into the remaining hot milk mixture. Cook over low heat, stirring continuously, for two more minutes.
4. Remove from the heat and stir in margarine. Stir in pumpkin puree, nutmeg, and cloves. The mixture will be a light brown color. Let cool and refrigerate.
5. Fill individual ramekins halfway with lightly packed crumbled gingerbread cake. Add a thin layer of pumpkin, and top with a layer of whipped cream.