• Lemon-Sugar Topping
• Stir together sugar and lemon zest in a small bowl until combined and set aside.

Muffins

• Heat oven to 425 degrees. Spray 12-cup muffin tin with vegetable oil spray or use liners.
• Bring 1 cup blueberries and 1 teaspoon of sugar to a simmer in small saucepan over medium heat.
• Cook, smashing berries with spoon several times and stirring frequently until berries have broken down and mixture is thickened, about 5-6 minutes.
• Transfer to a small bowl and allow to cool.
• Whisk the flour,baking powder and salt together in a large bowl.
• Whisk remaining 1 ⅛ cups of sugar and eggs together until combined do this for about a minute.
• Slowly whisk in butter, and oil until combined. Whisk in buttermilk and vanilla until combined.
• Fold egg mixture and remaining 1 cup blueberries into flour and mix until moistened.
• Batter will be lumpy and that's okay.
• Using an ice cream scoop or large spoon, divide batter evenly among the muffin cups.
• Spoon 1 teaspoon of the cooked berry mixture onto the batter.
• Using a skewer or knife, swirl the berry mixture into the batter making a figure-eight motion.
• Sprinkle lemon-sugar evenly over muffins.
• Bake until golden brown and toothpick inserted into the center comes out clean.
• Abut 17-19 minutes and rotate halfway through baking.
• Let muffins cool in pan and then transfer to wire rack.