Line 9-inch square pan with foil, with ends of foil extending over sides. Spray with cooking spray.
Mix Swerve and butter in large bowl until blended. Stir in eggs and the maple extract. Add coconut flour, almond flour, and baking powder and mix well. Stir in nuts. Pour into prepared pan.
Bake 35 minutes. Allow the dessert to cool in the refrigerator for an hour before cutting so that it can firm up a little.
Use foil handles to remove dessert from pan before cutting into squares.