Cheers to Happy: The Best Blueberry Muffin, ever...end of story...

Let's just get this on the table right now, Americas Test Kitchen is never wrong, never...and when they say they have the best recipe for something, you can be guaranteed that they have tested and retested the recipe...so with the abundant blueberries in the garden these were a given....during the test of the muffins, they wanted to add more berries but every time they did, it just made for a very heavy muffin...so they brilliantly made a slurry of berries and swirled them into the top of the muffins...they are not to sweet, and the texture is perfect!

Lemon Sugar Topping

1/3 cup sugar
Zest from one lemon (about 1 ½ teaspoons)

Muffins2 cups fresh blueberries
1 1/8 cups sugar, plus one teaspoon
2 ½ cups flour
1 ½ teaspoons baking powder
1 teaspoon table salt
2 large eggs
4 tablespoons unsalted butter, melted and cooled slightly
¼ cup vegetable oil
1 cup buttermilk
1 ½ teaspoons vanilla extract
Stir the sugar and zest together until combined; set aside.

Adjust oven rack to upper-middle position and heat oven to 425 degrees. Spray standard muffin tin with nonstick spray. Bring 1 cup blueberries and 1 teaspoon sugar to simmer in small saucepan over medium heat. Cook, mashing berries with a spoon several times and stirring frequently, until berries have broken down and mixture is thickened and reduced to ¼ cup, about 6-8 minutes. Transfer to bowl and cool to room temperature, 10-15 minutes.

Whisk flour, baking powder, and salt together in large bowl. Whisk remaining 1 1/8 cups sugar and eggs together in medium bowl until thick and homogeneous, about 45 seconds (remember, 80 strokes). 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. The batter will be very lumpy with spots of dry flour; do not overmix

Use an ice cream scoop or large spoon to divide batter equally among muffin cups (batter should completely fill cups and mound slightly). Spoon teaspoon of cooked berry mixture into center of each mound, pushing it below the surface. Using chopstick or skewer, gently swirl berry filling into batter using figure eight motion. Sprinkle lemon sugar evenly over muffins.

Bake until muffin tops are golden and just firm, about 17-19 minutes, rotating muffin tin (front to back) halfway through cooking time. Cool muffins in tin for about 5 minutes, then transfer to a wire rack and cool 5 more minutes before serving.