Preheat Oven: Preheat the oven to 425ºF (220ºC). Line a regular-sized 12-hole muffin pan with muffin patty liners and set aside.
Prepare Butter: Melt the butter and set it aside to cool slightly.
Mix Dry Ingredients: In a large mixing bowl, combine flour, sugar, baking powder, and salt. Whisk until well combined.
Add Eggs: Make a well in the center of the dry ingredients and add the eggs. Use your whisk or a fork to lightly beat them within the well.
Incorporate Wet Ingredients: Pour in the yogurt, milk, cooled melted butter, and vanilla. Fold gently until incorporated, ensuring not to over-mix.
Fold in Blueberries: Add the blueberries and fold them in gently, making sure not to over-mix the batter.
Fill Muffin Cups: Fill each muffin cup three-quarters full, dividing the batter evenly to make 12 muffins.
Bake: Start baking at 425ºF (220ºC) for 5 minutes. Then, reduce the oven temperature to 356ºF (180ºC) and continue baking for another 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean or with a few moist crumbs, not wet batter.
Cool in Pan: Remove the muffins from the oven and let them cool in the pan for 10 minutes.
Transfer to Rack: Move the muffins to a wire rack to cool completely. Enjoy!