1. Preheat oven to 350°. Beat butter at medium speed with an electric mixer 2 minutes or until creamy. Gradually add 2 cups sugar, beating 2 to 3 minutes. Add eggs, 1 at a time, beating until blended after each addition. Add sour cream and vanilla, beating until blended.
2. Whisk together flour and next 3 ingredients; gradually stir into butter mixture. (Batter will be thick.)
3. Place baking cups in muffin pans. Spoon batter into cups, filling two-thirds full.
4. Stir together pecans, 1/4 cup sugar, and cinnamon. Sprinkle pecan mixture over batter.
5. Bake at 350° for 20 to 25 minutes or until a wooden pick inserted in center comes out clean. Remove from pans, and cool completely on wire racks (about 12 to 15 minutes).