Heat oven to 350° F. Spray an 8-inch square baking pan with the nonstick spray. Line the pan with a piece of parchment, leaving an overhang on two sides; spray the parchment with the nonstick spray.
In a medium bowl, whisk together the flour, baking powder, and salt.
In a large bowl, whisk together the butter and sugars, then whisk in the eggs and vanilla. Stir in the flour mixture, then the pecans and chocolate chips.
Spread the batter in the prepared pan and bake until a toothpick inserted in the center comes out clean, 35 to 40 minutes.
Cool completely in the pan. Holding both sides of the paper overhang, lift the cake out of the pan, transfer to a cutting board, and cut into 16 squares. Note: Total Time includes cooling time.