Preheat oven to 375 degrees F. In a large bowl, beat vegetable oil spread and butter with an electric mixer on medium to high speed for 30 seconds. Gradually add sugar, about 2 tablespoons at time, beating on medium speed until well mixed, scraping side of bowl constantly. Beat on medium speed for 2 minutes more. Gradually add eggs, beating well. Beat in vanilla. Alternately add flour mixture and milk to butter mixture, beating on low speed after each addition just until combined. Fill muffin cups 2/3 full with batter.