Preheat the Oven:

Preheat your oven to 350°F (177°C). Spray a 24-count mini muffin pan with nonstick spray and set aside.

Mix the Dry Ingredients:

In a large bowl, whisk together the flour, baking powder, pumpkin pie spice, cinnamon, and salt.

Mix the Wet Ingredients:

In a medium bowl, whisk the melted butter and brown sugar together.

Add the egg, vanilla extract, pumpkin puree, and milk, whisking to combine until smooth.

Combine Wet and Dry Ingredients:

Pour the wet ingredients into the dry ingredients, then stir gently until just combined. Be careful not to overmix, as the batter will be thick.

Fill the Muffin Pan:

Using a small spoon, fill each muffin cup about 2/3 full with the batter.

Bake the Muffins:

Bake for 12-14 minutes, or until a toothpick inserted in the center comes out clean, or when lightly poked, the muffin bounces back.

Remove from the oven and allow to cool in the pan for 10 minutes.

Prepare the Cinnamon-Sugar Coating:

In a small bowl, mix together the granulated sugar and cinnamon.

Lightly dunk each warm muffin in the melted butter, then roll in the cinnamon-sugar mixture to coat generously.

Cool and Serve:

Place the coated muffins upright on a cooling rack to allow them to cool.

Repeat with the remaining muffins.