Blueberry muffins

Lemon-Sugar Topping:

• 1/3 cup sugar
• 1 1/2 teaspoons finely grated zest from 1 lemon

Muffins:

• 2 cups fresh blueberries, divided
• 1 1/8 cups plus 1 teaspoon sugar
• Juice from 1 lemon
• 2 1/2 cups unbleached all-purpose flour
• 2 1/2 teaspoons baking powder
• 1 teaspoon table salt
• 2 large eggs
• 4 tablespoons (½ stick) unsalted butter, melted and cooled slightly
• 1/4 cup vegetable oil
• 1 cup milk

Directions:

1. For the topping: In a small bowl, stir together sugar and lemon zest; set aside.
2. For the muffins: Preheat the oven to 425 degrees F. Line muffin cups with muffin liners or spray with nonstick cooking spray.
3. In a small saucepan over medium heat, bring 1 cup blueberries, juice from one lemon, and 1 teaspoon sugar to simmer. Cook, mashing berries with spoon and stirring frequently, until berries have broken down and mixture is thickened and reduced to ¼ cup, about 6 minutes. Transfer to small bowl and cool to room temperature, 10 to 15 minutes.
4. In a large bowl, whisk together the flour, baking powder, and salt.
5. In a medium bowl, whisk together remaining 1 1/8 cups sugar and eggs until thick, about 45 seconds. Slowly whisk in butter and oil until combined. Whisk in milk until combined. Using rubber spatula, gently fold egg mixture and remaining 1 cup blueberries into flour mixture until just moistened (do not overmix.)
6. Divide batter equally among prepared muffin cups (batter should completely fill cups and mound slightly). Spoon 1 teaspoon of cooked berry mixture into center of each mound of batter. Using a toothpick, gently swirl berry filling into batter. Sprinkle lemon sugar topping evenly over muffins.
7. Bake until muffin tops are golden and just firm, 17 to 19 minutes. Cool muffins in muffin tin for 5 minutes, then transfer to wire rack and cool 5 minutes before serving.