Cinnamon Rhubarb Muffins

Heat the oven to 375 degrees. Place paper baking cups into a 12 cup muffin pan or grease cups; set aside. Combine grown sugar and butter ina large bowl. Beat at medium speed until the mixture is creamy. Add sour cream and eggs. continue beating until well mixed Combine flour, baking soda and 1/2 teaspoon cinnamon in medium bowl. Stir flour mixture into sour cream mixture just until moistened. Gently stir in rhubarb. Divide batter evenly among prepared muffin pan cups. Stir together the 1 Tablespoon sugar and 1/2 teaspoon cinnamon. Sprinkle about 1/4 teaspoon mixture on top of each muffin. Bake for 25 to 30 minutes or until lightly browned. Let stand 5 minutes in pan; remove to wire cooling rack