Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, sugar, baking powder, and salt in a large bowl. Stir in pecans; make a well in center of mixture. Combine egg and next 4 ingredients (egg through margarine); stir well with a whisk. Add to flour mixture, stirring just until moist.
Spoon batter into 12 muffin cups coated with cooking spray. Bake at 400° for 22 minutes or until muffins spring back when touched lightly in center. Remove muffins from pans immediately; place on a wire rack.