Preheat oven to 375°F. Spray a metal 9"x13" pan with cooking spray, then line with parchment. Set aside.
In a large bowl or stand mixer cream together the butter, brown sugar and white granulated sugar. Add in egg, pumpkin puree, and vanilla and stir.
Beat in baking soda, baking powder, ginger, cloves, nutmeg, allspice, cinnamon, and flour and mix until fully combined. Stir in the chocolate chips.
Press cookie dough in the parchment lined pan, making sure it is spread out evenly with the back of a spoon or an offset spatula.
Bake for 25-30 minutes or until golden brown and set in the center. Let cool completely while making the frosting.
In a large bowl, cream butter, Mix in the powdered sugar and beat until smooth. As needed, mix in milk and vanilla extract with an electric mixer on medium-high until the frosting is smooth yet stiff, and able to hold a peak, about 3-5 minutes.
Spread frosting on cooled cookie bars and let it set. Top with sprinkles if you'd like. Enjoy!