Preheat the oven to 350°F. Line a cookie sheet with parchment paper. In a medium bowl stir together flour, PBfit Pumpkin Spice, baking powder, baking soda and salt.
In a large mixing bowl beat brown sugar, melted butter with a mixer on medium until combined. Add pumpkin, eggs, and vanilla; beat 1 minute. Add flour mixture, half at a time, beating well after each addition (batter will resemble thick cake batter).
Drop 1 Tbsp batter 1 ½ inches apart onto the prepared baking sheet. Bake for 12 to 14 minutes or until the tops spring back when lightly touched. Meanwhile, prepare frosting filling. Cool cookies on cookie sheet for 5 minutes. Remove; cool on the wire rack.
To prepare frosting: in a small saucepan heat 3 Tbsp butter over medium heat until melted. Continue cooking until butter turns a light golden brown, stirring occasionally. Cool 15 minutes. In a large bowl beat browned butter, cream cheese, and salt with a mixer on medium speed 2 minutes or until fluffy. Gradually beat in powdered sugar and PBfit Pumpkin Spice powder to reach spreading consistency. You may need to add a little milk if the frosting is too thick to spread.
Spread filling on the bottoms of half of the cookies, using about 2 teaspoons for each cookie. Top with remaining cookies, bottom side down; press gently to spread filling. Chill 30 minutes before serving.