In a blender, blend the milk, pumpkin, egg, oil, vinegar and vanilla.
In a large bowl combine flour, brown sugar, baking powder, baking soda, pumpkin pie spice and salt, then add wet ingredients and gently stir till combined.
The mixture will be somewhat thick.
Cook on a greased griddle or in a large pan, on low to medium heat. I used a small measuring cup to pour and spread out the batter. When bubbles start to form, flip over the pancakes. Mine cooked pretty quickly, and were heavier than usual since I used stone ground whole wheat flour. If you want them really light and fluffy, I would use all white flour or pastry flour.