Oh yes I often dispense with the crust and just bake it as a custard. This is not because I don't like the crust but because crust is fattening.   It cuts down on calories and if I'm really being weight conscious I use 2% milk and splenda instead of sugar. It still comes out pretty good. When lazy but not counting calories, I've used the pre-made graham cracker crust. It's hard to ruin pumpkin pie.