Absolutely. A pumpkin pie without a crust is simply a pumpkin custard, and saves more than half the work of making the traditional pie. We would butter the dish you bake it in, because otherwise it will stick like mad. You can also make individual servings by baking the filling in little ramekins or custard cups. The amount of time you bake it will depend on what dish(es) you use and how deep the filling is. A pie might take 45 minutes to set up; a deeper container will take longer, and custard cups will take significantly less time.
How do I determine how much orange oil to use in place of grated orange peel? What would the ratio be?