1. Mix together sugar and cinnamon. Set aside.
2. Grease muffin cups or line with muffin papers.
3. Combine first four ingredients.
4. In a separate bowl, beat butter and sugar until light and fluffy. Add egg. Slowly add dry mixture, beating until just combined.
5. Divide batter evenly among cups and sprinkle with topping. Bake muffins at 375°F 15 to 20 minutes, or until a tester comes out clean.
Cinnamon Sugar Muffins > Breakfast Casserole > Mixed Berries with White Chocolate Whipped Cream