Apple cinnamon muffins with a crumb Streusel topping and a light drizzle of vanilla glaze.
Preheat oven to 375 degrees.
In a small bowl, use a fork to combine melted butter, sugars, cinnamon, and flour and set aside.
In a medium bowl, combine flour, baking soda, baking powder, salt, and cinnamon and set aside.
In a mixer, beat butter and sugars together until light and fluffy- approximately 2 minutes. Add eggs, one at a time and mix well; then add vanilla.
Add yogurt/sour cream, milk, and dry ingredients and mix until just incorporated. Do not over-mix. Fold in chopped apple.
Line a muffin pan with cupcake liners (my favorite kind linked below). Divide batter evenly between cups (recipe makes up to 15 muffins or you can add extra batter to the dozen for bigger, over-filled muffins)
Divide crumble evenly between muffins, crumbling on top of each.
Bake for 15-17 minutes or until toothpick comes out with only wet crumbles on it. Important- Do not overcook.
Use a fork to whip together vanilla glaze. Allow muffins to cool before drizzling over the top.
You can find my favorite muffin cup liners HERE- they are sturdy and awesome and the prettiest brown color! (affiliate link)