6 tablespoons unsalted butter, at room temperature
3/4 cup sugar
1 1/4 cups sour cream
2 large eggs
2 cups unsweetened frozen blueberries, raspberries or blackberries (from a
3 tablespoons minced crystallized ginger
Preheat the oven to 375°. Coat 8 large muffin cups (3 1/4-inch diameter) with cooking spray.
In a large bowl, combine the flour, baking powder, baking soda and salt. In another bowl, beat the butter with 1/2 cup of the sugar until fluffy. Beat in the sour cream and eggs. Add the dry ingredients and stir just until evenly moistened; do not overmix. The batter will be very thick.
Spoon 3 tablespoons of the batter into each of the prepared muffin cups. Sprinkle with half of the frozen berries and crystallized ginger. Spoon another 3 tablespoons of batter on top and sprinkle with the remaining berries. Top with the remaining batter and sprinkle the muffins with the remaining 1/4 cup of sugar and the remaining ginger.
Bake in the middle of the oven for about 35 minutes, or until the tops are golden brown and springy to the touch and a cake tester inserted into the center comes out clean. Let the muffins cool in the pan for 5 minutes before turning out. Serve warm.
Let the muffins cool completely, then freeze in a resealable plastic bag for up to 1 month.