Mixed Berry Coffee Cake

Name: Mixed Berry Coffee Cake
Ingredients: 3/4 cup all-purpose flour; 2/3 cup packed light brown sugar; 1/2 cup old-fashioned rolled oats; 1 teaspoon ground cinnamon; Pinch fine salt; 5 tablespoons unsalted butter, at room temperature; 1 stick (8 tablespoons) unsalted butter, at room temperature, plus more, for the pan; 2 cups all-purpose flour; 1 teaspoon baking powder; 1/2 teaspoon baking soda; 1/2 teaspoon fine salt; 1 cup granulated sugar; 2 large eggs; 2 teaspoons pure vanilla extract; 1 cup sour cream; 2 cups frozen mixed berries, thawed