preheat oven to 350° line 9 x 13 pan with foil and grease with cooking spray

sift flour, baking powder, and salt together and set aside

in large bowl cream butter until light and fluffy. gradually beat in sour cream and sugar. beat eggs one at a time, then stir in vanilla. fold in flour mixture by hand until just incorporated. spread batter into prepared pan.

pecan topping: in medium bowl mix brown sugar, pecans and cinnamon. stir in melted butter until crumbly. sprinkle over cake batter in pan.

bake in preheated oven for 30 to 35 minutes, or until a toothpick inserted into center of cake comes out clean. let cool in pan for 10 minutes then turn out onto a wire rack and remove foil.