Why this recipe works: Blueberry muffins should be packed with blueberry flavor and boast a moist crumb. But too often, the blueberry flavor is fleeting, thanks to the fact that the berries in the produce aisle have suffered from long-distance shipping. We wanted blueberry muffins that would taste great with blueberries of any origin, even the watery supermarket kind.

To intensify the blueberry in our muffins, we tried combining blueberry jam with fresh supermarket blueberries. The muffins baked up with a pretty blue filling, but tasters thought the jam made them too sweet. To solve this, we made our own fresh, low-sugar berry jam by simmering fresh blueberries on the stovetop with a bit of sugar. Adding our cooled homemade jam to the batter along with fresh, uncooked berries gave us the best of both worlds: intense blueberry flavor and the liquid burst that only fresh berries could provide.

As for the muffin base, we found that the quick-bread method—whisking together eggs and sugar before adding milk and melted butter, and then gently folding in the dry ingredients—produced a hearty, substantial crumb that could support a generous amount of fruit. We found that an equal amount of butter and oil gave us just the right combination of buttery flavor and moist, tender texture. To make the muffins even richer, we swapped the whole milk for buttermilk. Finally, for a nice crunch, we sprinkled lemon-scented sugar on top of the batter just before baking.

Lemon-Sugar Topping:

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

Muffins:

• 2 cups fresh blueberries (about 10 ounces), picked over
• 1 1/8 cups sugar (8 ounces) plus 1 teaspoon
• 2 1/2 cups unbleached all-purpose flour (12 1/2 ounces)
• 2 1/2 teaspoons baking powder
• 1 teaspoon table salt
• 2 large eggs
• 4 tablespoons (1/2 stick) unsalted butter , melted and cooled slightly
• 1/4 cup vegetable oil
• 1 cup buttermilk (see note)
• 1 1/2 teaspoons vanilla extract

1. FOR THE TOPPING: Stir together sugar and lemon zest in small bowl until combined; set aside.
2. FOR THE MUFFINS: Adjust oven rack to upper-middle position and heat oven to 425 degrees. Spray standard muffin tin with nonstick cooking spray. Bring 1 cup blueberries and 1 teaspoon sugar to simmer in small saucepan over medium heat. Cook, mashing berries with spoon several times 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.
3. Whisk flour, baking powder, and salt together in large bowl. Whisk remaining 11/8 cups sugar and eggs together in medium bowl until thick and homogeneous, about 45 seconds. Slowly whisk in butter and oil until combined. Whisk in buttermilk and vanilla until combined. Using rubber spatula, fold egg mixture and remaining cup blueberries into flour mixture until just moistened. (Batter will be very lumpy with few spots of dry flour; do not overmix.)
4. Following photos below, use ice cream scoop or large spoon to divide batter equally among prepared muffin cups (batter should completely fill cups and mound slightly). Spoon teaspoon of cooked berry mixture into center of each mound of batter. Using chopstick or skewer, gently swirl berry filling into batter using figure-eight motion. Sprinkle lemon sugar evenly over muffins.
5. Bake until muffin tops are golden and just firm, 17 to 19 minutes, rotating muffin tin from front to back halfway through baking time. Cool muffins in muffin tin for 5 minutes, then transfer to wire rack and cool 5 minutes before serving.

• If buttermilk is unavailable, substitute 3/4 cup plain whole-milk or low-fat yogurt thinned with 1/4 cup milk.