Prepare a muffin pan with cupcakes liners and grease the liners generously with butter then set aside.
Add butter, brown sugar, and sugar to a large bowl and beat using an electric hand mixer at medium-high speed until the mixture turns light and creamy. (This could take around 2-3 minutes.)
Next add in the eggs, vanilla, lemon juice, and lemon zest to the butter-sugar mixture and beat using an electric hand mixer on medium-high speed until combined well.
In a separate bowl mix the flour, salt, and baking powder.
Slowly fold your dry ingredients into the wet ingredients alternating between milk and dry ingredients until all your milk and dry ingredients have been mixed into your wet. Be careful not overmix as that can make your muffins dense.
Now, gently fold in the blueberries but again do not overmix.
Preheat the oven to 425 degrees F and let the batter rest while you preheat the oven.
Divide the batter between the muffin cups, filling almost to the top. Sprinkle the sugar on the top for a nice crunch.
Bake in a preheated oven at 425 degrees F for 6 minutes, then keep the muffins in the oven and reduce the temperature to 375 degrees F and bake for another 18-20 minutes or until the muffins turn golden brown on top and the toothpick inserted in the middle comes out clean.
Allow the muffins to cool in the pan for 5 to 10 minutes before serving.