Combine the ingredients for the cinnamon butter and set aside.
Add the vinegar to the milk. Allow to sit for 10 minutes, or until curdled.
Add the flour, baking powder, baking soda, pumpkin pie spice, and salt together. Whisk to combine and set aside.
Add the pumpkin puree, sugar, eggs, vanilla, milk mixture, and melted butter together. Whisk until combined.
Add the dry ingredients to the wet ingredients and mix until there are no obvious dry bits left, but the mixture has some lumps. Allow to rest for 5 minutes.
Now add a bit of butter to your skillet over medium heat. Add about ¼ cup of batter and cook until air bubbles begin to form all over the batter (about 2.5 minutes). (You may need to lower the heat in order to cook it through without burning the top of the pancake).
Flip the pancake and allow to cook through (about 1-2 more minutes). Remove to a plate and repeat until the batter is used up.
Serve immediately with the cinnamon butter and maple syrup.