Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). Line a muffin tin with paper liners and set aside. 

In a large bowl, combine flour, sugar, baking powder, baking soda, and salt. Add sour cream, butter, milk, vanilla, and egg and whisk well.

In a separate bowl, mix streusel ingredients until you have a crumbly consistency. ‎

Place one tablespoon batter on the bottom of each muffin cavity. Sprinkle with one teaspoon streusel topping and some blueberries. Add an additional tablespoon of batter and then additional streusel topping. 

Bake for 25 minutes, until a toothpick inserted in a muffin comes out clean.