In a small bowl, whisk together the flour, sugar, baking powder, and salt and set aside.
Use a fork to mix in the melted butter. Mix in the egg white until combined.
Fold in the yogurt and vanilla extract to the batter, the batter should remain thick.
With a mini rubber spatula gently fold in the blueberries
Place 1 paper liner n a muffin tin and spoon the batter into the liner.
Bake in a 400° preheated oven for 18-20 minutes. Check for doneness by inserting a toothpick into the middle of the muffin, if it comes out clean the muffin is done. Cool 10 minutes before removing from muffin tin.
Notes
Preheat the Oven: Before you put your muffin into the oven make sure to preheat it. This will help it rise properly and cook evenly.Avoid Overmixing: overmixing can result in a tough muffin. Mix until both the wet and dry ingredients are just combined.Adjust the Sweetness: I tend to use lower amounts of sugar, if you like your muffins sweeter, add an additional tablespoon of sugar.Add Blueberries Last: Mix your batter first, then gently fold in the blueberries to avoid squishing them. Lightly coat fresh blueberries with sugar before folding them into the muffin batter. Fresh or Frozen Blueberries: If using frozen, to prevent bleeding don't thaw them before adding to the batter.Let it Cool: Let your muffin cool in the baking tin or ramekin for a few minutes then remove and transfer the muffin to a wire rack to finish cooling.Substitute blackberries, and raspberries, or combine for a triple berry muffin.