Cranberry Vanilla Coffeecake

Name: Cranberry Vanilla Coffeecake
Ingredients: 1/2 vanilla bean, split lengthwise; 1 3/4 cups sugar; 2 cups fresh or thawed frozen cranberries (6 ounces); 2 cups plus 1 tablespoon all-purpose flour, divided; 2 teaspoons baking powder; 3/4 teaspoon salt; 1 stick plus 1 tablespoon unsalted butter, softened, divided; 2 large eggs; 1/2 cup whole milk; Garnish: confectioners sugar