Combine sugar, 1 cup flour, and baking powder; mix well and set aside.
Combine butter and chocolate syrup in a heavy saucepan; bring to a boil, stirring constantly. Remove from heat and cool. Gradually stir into flour mixture. Stir in eggs and vanilla. Dredge pecans in remaining 1/2 cup flour; stir into batter.
Pour batter into a greased and floured 9-inch square pan. Bake at 350° for 55 to 60 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes; cut into squares to serve.
Oxmoor House Homestyle Recipes