Preheat the oven to 350℉.
Into a large bowl, add butter and sugars. Cream together until light and fluffy.
Add room temp egg and mix well. Then add vanilla extract and mix.
Add 1 cup of flour and mix. Then add 1 cup of milk and sour cream and mix well. Then add the other cup of flour along with salt, baking soda, and baking powder. Mix until just combined. Do not over mix or the muffin will be tough.
For the filling, just mix the sugar and cinnamon in a small bowl.
For the crumble topping, mix the flour, butter, brown sugar, and cinnamon. Mix well to form crumbles.
Line your muffin tin with paper liners. Using a 2 inch cookie scoop, add 1 scoop of batter to the liners. Top with cinnamon sugar (evenly distribute the cinnamon sugar among the muffins) and then add another scoop of batter on top. Top with lots of crumble topping.
Bake at 350℉ for 25-30 mins or until a knife comes out clean. Time may vary depending on your oven.
****Optionally, you can make a sugar glaze and drizzle it on top of each muffin once cooled. The sugar glaze is just 1 cup of confectioners sugar with 1 1/2 tbsp of milk, 1/2 tsp vanilla ext.