Preheat oven to 350 degrees and spray a mini muffin pan with nonstick cooking spray and set aside.
In a medium bowl, combine flour, baking powder and salt. Stir to combine.
In a small bowl whisk together the melted butter, sugar, egg, lemon juice, vanilla extract, milk, and yogurt until combined. Add the flour mixture and mix until all ingredients are incorporated. Fold in the blueberries just until combined.
Evenly distribute the muffin batter into the muffin pan and bake for 15-18 minutes. Insert a toothpick in the center of a muffin and make sure it comes out clean. If it does, the muffins are baked all the way. Cool for a few minutes before serving, enjoy!