Place rack in the center of the oven then preheat to 350 degrees. Line muffin tin with 12 paper liners.
In a large mixing bowl, combine flour, sugar, baking powder, baking soda and salt. Mix in lightly beaten egg, milk, vanilla, lemon juice and melted butter until just combined.
Fold in blueberries. Scoop batter into muffin liners, filling each one about ¾ full.
In separate small bowl, mix together the granulated sugar, brown sugar, flour, salt and cinnamon. Cut in butter or mash with fork until mixture resembles coarse crumbs. It does not have to be a uniform paste, just mash the butter into the dry ingredients until they’re combined—it’s okay if there are still some dry spots. Sprinkle topping over unbaked muffins.
Bake 28–30 minutes, but make sure to check on them at the 25 minute mark. The muffins are done when a toothpick comes out with a few moist crumbs attached and the centers are firm. Cool the muffins for about 10 minutes before serving. Enjoy!
One Last Thing
Need to make a bigger batch? No problem—just double the ingredients and you’re good to go!