Preheat oven to 425 degrees F. Spray 18 muffin cups (1 1/2 tins) with nonstick cooking spray containing flour or grease and flour muffin cups.
In a large bowl, whisk flour, baking powder and salt together. Add blueberries and toss until evenly coated.
Whisk sugar and eggs together in a separate medium bowl until combined. Slowly whisk in cooled butter and oil into sugar/eggs until combined, followed by milk, sour cream, vanilla and lemon extract until combined.
Using a rubber spatula, fold egg mixture into flour mixture just until moistened, don’t overmix! (mixture will be lumpy)
Using an ice cream scooper or large spoon, divide batter evenly among 18 prepared muffin cups.*
Bake muffins at 425 degrees F for 17-19 minutes or until toothpick inserted into the center of muffins comes out clean. Let muffins cool in tin for 5 minutes then transfer to wire rack to cool completely before glazing.
To prepare the Lemon Glaze, beat all the ingredients together until smooth, adding additional lemon juice for tangier, more sugar for sweeter. If you desire a thinner glaze, add milk one teaspoon at a time. Lightly glaze cooled muffins.
Store leftover muffins in an airtight container for up to 5 days.