Preheat your oven to 375°F (190°C).
Line your muffin tin with parchment liners or grease it lightly.
In a large mixing bowl, whisk together the flour, baking powder, baking soda, and salt.
In another large bowl, beat together the softened butter, granulated sugar, and brown sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
Alternate adding the dry mixture and the buttermilk and milk to the butter mixture, mixing until just combined.
Fold the blueberries into the batter gently using a rubber spatula.
For the topping, mix the softened butter, flour, brown sugar, and cinnamon until crumbly.
Spoon the batter into the muffin tin, filling each cup about 3/4 full, and sprinkle the topping over each muffin.
Bake for 18-22 minutes, or until a toothpick inserted comes out clean.
Cool in the tin for 5 minutes before transferring to a wire rack.