Whisk together the flour, baking powder, baking soda, salt, and pumpkin pie spice.
In a separate bowl, whisk together the pumpkin, melted butter, vanilla extract, brown sugar, milk, and eggs.
Add the dry ingredients to the wet, and mix until just combined. Do not over mix.
Spray a mini muffin tin with olive oil cooking spray.
Distribute the muffin batter into the 24 mini muffin cups using a mini cookie scoop.
Bake the mini pumpkin muffins at 350 degrees for 14-17 minutes, or until a toothpick inserted comes out clean.
Remove the muffins onto a wire cooling rack.
Stir together the cinnamon and sugar topping in a bowl. Melt the butter in a separate bowl in the microwave.
While the muffins are still warm, brush each one first with the melted butter using a pastry brush, then roll the muffin immediately in the cinnamon sugar until coated on all sides. Repeat with the remaining muffins and return them to the wire cooling rack to cool completely once finished.
Notes
While you can dunk the muffins into the butter, I prefer using a pastry brush instead to brush the butter on. This allows for a more even distribution as well as ensures that they are not too greasy.