Coffee Cake Muffins

1: Preheat the oven to 350°F.

2: If using a mini muffin tin, coat each cup with butter and a dusting of flour to prevent sticking.

3: In a bowl, mix together the Greek yogurt, eggs, butter, and vanilla until smooth (a few lumps may remain).

4: Pour in the flour, baking soda, baking powder, and salt, and fold until everything is incorporated.

5: Add the buttermilk and fold in to loosen the batter.

6: To make the crumble, mix together the brown sugar, flour, cold butter, and cinnamon until it resembles wet sand.

7: Fill each muffin cup halfway with the batter.

8: Place a layer of the crumble on top of the batter.

9: Scoop more batter on top to cover the crumble.

10: Bake at 350°F for 14-17 minutes for mini muffins or 22-25 minutes for large muffins until done.