1/4 cup unsweetened cocoa powder, plus more for pan
3/4 cup all-purpose flour
1 teaspoon ground ginger
1 teaspoon pumpkin pie spice
1/2 teaspoon baking soda
1/2 cup packed dark brown sugar
1/4 cup molasses
1 large egg
1/4 cup sour cream
1/2 cup semi sweet chocolate chips
confectioner's sugar for dusting
Preheat oven to 350F degrees. Butter an 8-inch square baking pan. Line bottom with strip of parchment paper, leaving an overhang on two sides, butter paper. Dust paper and sides of pan with additional cocoa powder; set aside.
In medium bowl, whisk together cocoa, flour, ginger, pumpkin pie spice, and baking soda. Set aside. In large bowl, whisk together butter, brown sugar, molasses, egg and sour cream until smooth. Add flour mixture. Stir just until moistened (do not overmix). Stir in chocolate chips. Transfer batter to prepared pan and smooth top.
Bake until toothpick inserted comes out clean (about 30 to 35 minutes). Transfer to wire rack and let cool completely. Using paper overhang, lift gingerbread from pan. Transfer to cutting board and cut into 16 squares. Before serving, dust with powdered sugar.