Preheat oven to 350 degrees. Line a 12 cup muffin pan with paper liners. Spray the paper with non-stick cooking spray.

For the crumble, mix together the 2/3 sugar, flour, and the cinnamon. Using a fork, cut in the butter until crumbles are formed; set aside.

For the muffins, In a large bowl, whisk together the flour, baking powder, ground cinnamon, salt and the baking soda; set aside.

In a medium bowl, using a fork or a whisk lightly beat the eggs. Stir in ¾ cup sugar, melted butter, sour cream and the vanilla extract. Stir the wet mixture into the flour mixture just until combined. Stir in ½ of the crumble (approximately ¾ cup) into the batter.

Spoon the batter evenly into the 12 muffin cups. Top with the remaining crumble. Bake for 24 to 28 minutes or until a toothpick inserted into the center comes out clean.

Allow to cool until easily handled then transfer to a wire rack to cook completely.