Preheat oven to 350F and line a 9-inch square baking pan with parchment paper. Set aside.
Place pumpkin puree in the middle of a kitchen towel. Gather up edges of kitchen towel and gently squeeze pumpkin over a sink or bowl until all the liquid is squeezed out.
In a large bowl, whisk pumpkin puree, melted butter, brown sugar, granulated sugar, egg, and vanilla until smooth.
In a separate medium bowl, combine flour, pumpkin pie spice, baking powder, baking soda, and salt. Fold flour mixture into liquid mixture until batter is just combined.
Spread batter in an even layer in prepared baking pan. Bake bars at 350F 25-30 minutes until a toothpick inserted in center of bars comes out clean. Cool bars completely on a wire cooling rack.
Cream Cheese Frosting
Place cream cheese and butter in a large bowl (or a stand mixer fitted with paddle attachment) and use an electric mixer to beat on medium speed until 2-3 minutes until creamy.
Add vanilla and powdered sugar to cream cheese mixture and beat an additional 2-3 minutes until frosting is completely smooth and creamy. Beat in 1-2 teaspoons milk and more as needed to thin frosting.
Spread frosting over cooled bars and sprinkle with additional pumpkin pie spice. Cut bars into squares and serve. Enjoy!
Notes
Storing InstructionsStore bars in refrigerator up to 4 days. Bring bars to room temperature for 30 minutes before serving.