Add the spice cake mix to the crock pot.
In a medium bowl, combine the pumpkin and evaporated milk, then pour over the spice cake mix. Do not mix.
Set crock pot to high and cook for 1 hour.
Switch crock pot setting to low and cook for 1 more hour.
Mix everything thoroughly, then cook for an additional 1-2 hours on low, until the cake has set.
Best served warm. Garnish with caramel sauce, walnuts, or vanilla ice cream if desired!