4tablespoonsbutterslightly softened and cut into small pieces
2 1/4cupsall-purpose flour
1 ½cupsfresh blueberries
Preheat oven to 350 degrees F. Grease 2 12-cup muffin pans with nonstick cooking spray. Set aside.
Combine ingredients for the streusel topping in a small bowl, using a pastry cutter or a fork to cut the butter into the dry ingredients until well incorporated. (It should be the consistency of wet sand.) Set aside.
In a medium bowl, whisk together flour, baking powder, baking soda and salt. Set aside.
In a large bowl and with an electric mixer on medium speed, beat butter, oil and sugars on medium speed until smooth. Add the eggs, one at a time, beating well after each addition.
Reduce mixer speed to low, and then mix in the sour cream and vanilla just until combined.
Gradually beat in the flour mixture, just until combined (do not overmix).
Gently fold in 1 cup of blueberries.
Layer the batter and streusel into the muffin cups: Spoon about 1 ½-2 tablespoons of batter into each muffin tin. Top evenly with half of the streusel mixture. Spoon remaining batter evenly over the streusel, then top with remaining streusel.
Place the remaining blueberries evenly on top of the muffins. (We got 3 berries per muffin and had a few leftover).
Bake muffins for about 20 minutes, or until the tops are golden and a toothpick inserted comes out clean.
Remove muffins from the oven and let cool in the muffin pan for 5-10 minutes before transferring to a cooling rack.