2 cups all purpose flour 1 tablespoon baking powder 1/2 teaspoon salt 2 large eggs 1 cup sour cream 1 teaspoon milk 2/3 cup sugar 8 tablespoons warm melted butter (1 stick) 1 teaspoon vanilla 11 oz of fresh blackberries, cut in half (You can use frozen blackberries if fresh are not available.)
Position rack in center of oven. Preheat oven to 400°F. Grease a standard 12 muffin pan or line with paper muffin cups.
Whisk together the flour, baking powder and salt in a large bowl.
In a separate bowl, whisk together eggs, sour cream, milk, sugar, butter and vanilla.
Add the wet mixture to the dry mixture and mix together with a few light strokes, just until the dry ingredients are moistened. Add the berries. (If you are using frozen berries, defrost them first, then drain the excess liquid, then coat them lightly in flour.) Do not over-mix! Over-mixing will cause the muffins to be dense, not fluffy. The batter should not be smooth.
Divide the batter evenly among the muffin cups. Bake until a toothpick inserted into the middle of 1 or 2 of the muffins comes out clean, 17-20 minutes (or longer).
Let cool for 2 to 3 minutes before removing from the pan. If not serving hot, let cool on a rack.
Serve as soon as possible, preferably within a few hours of baking.