Cinnamon Rhubarb Muffins

1. Preheat the oven to 375°F (190°C). Grease a muffin tin or line with paper liners.

2. In a large bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and ground cinnamon.

3. In another bowl, combine the sour cream, milk, vegetable oil, vanilla extract, and egg. Mix well.

4. Add the wet ingredients to the dry ingredients and stir until just combined. Do not overmix.

5. Gently fold in the chopped rhubarb.

6. Divide the batter evenly among the muffin cups, filling each about 2/3 full.

7. In a small bowl, mix together the sugar and ground cinnamon for the topping. Sprinkle over the batter in each muffin cup.

8. Bake for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.

9. Allow the muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.