Preheat your oven to 375 degrees and line two 12-cup muffin tins with paper liners.

In a large bowl, cream together the melted butter and sugar for 2-3 minutes until well combined. You can use a stand mixer or a hand mixer for this step.

Add the eggs and vanilla extract to the butter-sugar mixture, and then incorporate the buttermilk and sour cream. Once everything is thoroughly combined, gently fold in the flour, salt, and baking powder. Finally, fold in the fresh blueberries.

Scoop approximately 2 tablespoons of the batter into each muffin cup in the tins.

Place both muffin tins on the top rack of your preheated oven and bake for 27-29 minutes. Remember to rotate the tins at the halfway mark for even baking.

Once the muffins turn golden brown and a toothpick inserted into the center comes out clean, they are ready. Remove them from the oven.

Store the muffins in an airtight container in the refrigerator, where they can stay fresh for up to a week. Enjoy your delicious homemade blueberry muffins!