Mix brown sugar, cinnamon, and flour together in a small bowl. Add the butter and mix together until crumbly. Set aside.

Beat unsalted butter and granulated sugar together on high speed until smooth and creamy, about 2 minutes. On medium speed, add eggs one at a time, beating well after each addition. Beat in vanilla extract until combined.

Whisk all-purpose flour, baking soda, baking powder, and salt in a medium bowl.

With the mixer running on low speed, add the dry ingredients and milk alternatively into wet ingredients and beat until fully incorporated. Fold in blueberries.

Spoon about 1/4 cup each of the batter into 12 greased or lined muffin cups. Evenly sprinkle the streusel topping onto each muffin top gently pressing it down into the surface so it sticks. Bake in 425 F oven for 5 minutes, then reduce temperature to 350 F and bake for an additional 15 minutes or until a toothpick inserted in the center comes out clean. Allow to cool for 5 minutes in the pan before removing onto wire racks to finish cooling.