Preheat your oven to 375°F (190°C) and prepare a muffin tin by lining it with paper liners or lightly greasing it.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, beat the softened butter and cream cheese together until smooth and creamy.

Gradually add the sugar, beating until well incorporated.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

Slowly add the dry ingredients to the wet mixture, alternating with the milk. Start and end with the flour mixture, mixing just until combined.

Gently fold in the blueberries, being careful not to overmix.

Divide the batter evenly among the muffin cups, filling each about two-thirds full.

Bake for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.

Let the muffins cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely.