Crumb Cake

Name: Crumb Cake
Prep time: 25 min
Cook time: 45 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 2½ sticks (10 ounces) unsalted butter, melted; ½ cup granulated sugar; 1½ cups (packed) light brown sugar; 2 teaspoons ground cinnamon; ½ teaspoon salt; 4 cups cake flour, spooned into measuring cup and leveled-off; Confectioners' sugar (for dusting); 2 cups all-purpose flour, spooned into measuring cup and leveled-off; 1 teaspoon baking soda; 1 teaspoon baking powder; ¼ teaspoon salt; 1 stick (4 ounces) unsalted butter, softened; 1 cup granulated sugar; 3 large eggs; 1 teaspoon vanilla extract; 1 cup sour cream