Instructions:
1. Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or grease the muffin cups.
2. In a mixing bowl, whisk together the flour, baking powder, baking soda, salt, and ground cinnamon. Set aside.
3. In another bowl, cream together the softened butter and 1 cup of granulated sugar until light and fluffy.
4. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
5. Gradually add the dry ingredients to the wet ingredients, alternating with the yogurt or buttermilk, beginning and ending with the dry ingredients. Mix until just combined; do not overmix.
6. In a small bowl, combine 1/4 cup granulated sugar and 1 teaspoon ground cinnamon.
7. Using an ice cream scoop or spoon, fill each muffin cup with batter until about two-thirds full.
8. Bake in the preheated oven for 18-20 minutes or until the muffins are lightly golden and a toothpick
9. While the muffins are still warm, dip the top of each muffin into the melted butter, then into the cinnamon-sugar mixture to coat the tops.
