In a large mixing bowl beat together the butter, pumpkin, and brown sugar.
Add the egg, salt, vanilla, and baking powder and mix well.
Add flour and mix until combined. Stir in chocolate chips.
Spread into a greased 9x13" pan and bake 20 minutes or until a toothpick inserted into the center on the bars comes out clean or with moist crumbs. Do not over bake.
Let cool completely before frosting.
In a mixing bowl, beat together butter, cream cheese, vanilla, and powdered sugar until smooth and creamy.
Spread over cooled bars and sprinkle with chocolate chips.