Preheat oven to 375 degrees Fahrenheit. Prepare two muffin tins with cupcake liners.

In a large bowl, whisk together the flour, sugar, baking powder and kosher salt. Set aside.

In a small bowl, whisk together eggs, yolk, lemon zest, milk, lemon juice and oil until well combined.

Pour the wet ingredients into the bowl of dry ingredients. Mix gently until no more dry flour is found. Batter will have some lumps and that is good. Do not overmix.

Fold in the fresh blueberries.

Using a one-fourth-cup measuring spoon or an ice cream scoop, portion the batter into the prepared muffin pans.

Now make the crumb topping. In a small bowl, add the butter, sugar and flour. Use a fork or your fingers to mix until well combined and crumbly.

Sprinkle evenly over all of the muffins. Try to keep it inside the muffin cups. You don’t want the excess crumb mixture to burn on the top of your pan.

Bake for 18–20 minutes at 375 degrees. Allow the muffins to cool completely on a wire rack.

Now mix the lemonade glaze. In a small bowl, add lemon juice and powdered sugar. Whisk until very smooth. If the glaze is too tight to drizzle, then add an additional one-fourth teaspoon of lemon juice and mix.

Drizzle the glaze over your finished muffins and serve!