Preheat the oven to 350F.
In a large bowl, mix the pumpkin, sugar, oil, egg and vanilla. In another bowl, stir together the dry ingredients; add to the pumpkin mixture and stir just until combined.
Fill paper-lined muffin cups and if you like, sprinkle with coarse sugar. If you're filling them, poke a hole in the top of each with the handle of a wooden spoon and add a small spoonful of the cream cheese mixture. Bake for 25 minutes, or until springy to the touch.