Step 1

Preheat oven to 400 degrees Fahrenheit. Line a muffin tin with paper liners, spray liners with cooking spray, and set aside.

Step 2

In a medium bowl, combine sugar, flour, cinnamon and melted butter. Mix with a fork until a crumbly texture forms. Set aside.

Step 3

In a large bowl, sift together flour and baking powder. Add cinnamon, nutmeg, and sugar and whisk to combine. Set aside.

Step 4

In another medium bowl, add egg, egg yolks, vanilla and buttermilk and whisk to combine all ingredients. Add melted butter and whisk to combine.

Step 5

Make a well in the center of flour mixture and pour liquid ingredients into well. Fold batter with a rubber spatula until all ingredients are just combined.

Step 6

Fill each muffin cup almost all the full (a little over 3/with muffin batter and then generously top each muffin with crumble topping. You may need to break up the crumble topping in between your fingers. These will be big muffins! I use a cookie scoop to fill muffin cups.

Step 7

Bake muffins at 400 degrees for 25-30 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs. Allow muffins to cool in the pan for 10 minutes then remove them from the pan and transfer to a wire rack to cool completely.

Step 8

Serve muffins warm or room temperature. Enjoy!