Preheat oven to 375°F. Line 6 muffin cups with liners or grease well.
In a small bowl, combine the flour, baking powder, and salt.
Place frozen blueberries in a small bowl and sprinkle 1 teaspoon of the flour mixture over them. Gently toss to coat.
In a medium bowl, beat together the white sugar, brown sugar and butter until light and fluffy.
Beat in the egg. Then mix in the milk. Beat in the vanilla extract and lemon peel.
Mix the dry flour mixture into the wet mixture just until combined, being careful not to over mix.
Gently fold in the blueberries.
Spoon batter into prepared muffin cups.
TOPPING
In a small bowl, combine the sugar, flour, and cinnamon.
Cut in the butter with a fork.
Sprinkle streusel topping mixture over each muffin cup batter.
Bake for 20 to 25 minutes or until the centers of each muffin test are done by inserting a toothpick and checking that it comes out dry. Remove from oven and let cool on a wire rack.
Notes
Use frozen blueberries right from the freezer. This prevents them from bleeding into the batter and turning it blue. If you thaw the berries, they release their juices which can cause discoloration and affect the texture of your muffins.Toss the blueberries in flour. This will help prevent them from sinking to the bottom of your muffins during baking.Avoid over-mixing your batter. Mix the batter just until combined, then fold in the blueberries. Over-mixing can lead to tough and dense muffins.Don't skip the lemon zest. Mixing freshly grated lemon zest into the batter enhances the flavor. Although fresh is best, you can use dried if that's all you have.Use liners to prevent the muffins from sticking to the pan. Although you can grease the cups, liners will make removing the muffins from the pan much more effortless.