I have always been a big fan of blueberry muffins and these are the best I have eaten so far. These are very easy to make. I think the key is adding the blueberry mixture in at the end eliminates the muffins from turning blue and becoming soggy. If a recipe calls for too many blueberries, they will get too wet and will fall apart.
Lemon Sugar Topping
1/3 cup sugar
1 1/2 teaspoons finely grated zest from 1 lemon
2 cups fresh blueberries
1 1/8 cups sugar plus 1 teaspoon
2 1/2 cups flour
2 1/2 teaspoons baking powder
1 teaspoon table salt
2 large eggs
4 tablespoons unsalted butter, melted and cooled slightly
1/4 cup vegetable oil
1 cup buttermilk
1 1/2 teaspoons vanilla extract
1. For the topping: Stir together the sugar and lemon zest in a small bowl until combined; set aside.
2. For the muffins: Adjust the 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 has thickened and reduced to 1/4 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 1 1/8 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 cum blueberries into the flour mixture until just moistened. Batter will be lumpy with a few spots of dry flour; do not overmix.
4. Use ice cream scoop or large spoon to divide batter equally between prepared muffin pans. Batter should completely fill cups. Spoon one teaspoon of cooked berry mixture into center of batter. Using a skewer, gently swirl berry filling into batter using figure-eight motion. Sprinkle with lemon sugar evenly over muffins.
5. Bake until muffin tops are golden and just firm, 17 to 20 minutes. Rotate muffin tins half way through baking. Cool muffins 5 to 10 minutes, then transfer to wire rack and cool 5 minutes longer before serving.