Preheat oven to 325°F. Lightly grease a 9x13 pan with butter, or line with paper. Sift together flour, baking powder, and salt. Cream together butter and sugar. Add egg and vanilla and mix until light and fluffy. Slowly add flour mixture to butter mixture, mix until combined. Add pecans and stir to distribute. Press dough into greased pan. Sprinkle generously with cinnamon sugar and with chopped pecans and very lightly press into the top of dough.

Bake 16-18 minutes, or until beginning to brown around edges. Do not allow bars to actually brown. Cool in pan 15 minutes and cut into bars. If they are too soft to cut, cool for a few more minutes. Remove carefully to a wire rack to cool completely before storing in an airtight container.