Preheat oven to 350F (177C) and line a muffin tin with paper liners. Set aside.
Place your butter pieces in a large, microwave-safe bowl and microwave until melted. Set aside.
In a separate large bowl combine flour, sugars, baking powder, baking soda, salt, pumpkin spice, and cinnamon. Whisk until well-combined. Set aside.
Return to your bowl with the melted butter and ensure that it is not hot to the touch (should not feel very warm) Add eggs and vanilla to the butter mixture and stir or whisk well.
Add pumpkin puree and milk to the pumpkin mixture and stir until completely combined.
Gradually stir your dry ingredients into your wet until completely combined, taking care to not over-mix the batter.
Evenly divide cupcake batter into prepared muffin tins (filling each about ⅔-¾ full) and bake on 350 for 20 minutes (toothpick inserted in center should come out mostly clean with only few crumbs).
Allow to cupcakes to cool completely before icing.
Brown Sugar Cream Cheese Frosting
In the bowl of a stand mixer with a paddle attachment (or in a large bowl using an electric mixer) beat together cream cheese and butter, until well-creamed.
Add brown sugar, vanilla extract, and salt and beat on medium-high speed until well-combined (about 15-30 seconds). Pause mixer to scrape down sides of bowl, and then beat again to make sure all ingredients are combined.
Reduce mixer speed to low and gradually, about ½ cup at a time, add powdered sugar until combined. Scrape sides and bottom of bowl again.
If using heavy cream, add now (1 Tablespoon at a time) and beat on high speed for 30 seconds — until frosting is smooth and silky. Scrape down sides of bowl once more and beat briefly.
Spread or pipe frosting over cooled cupcakes.
Enjoy!