Spiced Banana Bread Coffee Cake

Name: Spiced Banana Bread Coffee Cake
Ingredients: 2 cups all-purpose flour; 1 teaspoon baking powder; 1 teaspoon garam masala; 1/2 teaspoon baking soda; 1/2 teaspoon salt; 10 tablespoons unsalted butter, at room temperature; 1 cup granulated sugar; 2 large eggs; 1 tablespoon pure vanilla extract; 1 cup mashed overripe bananas (2 to 3 bananas); 1/2 cup sour cream; 3/4 cup all-purpose flour; 2/3 cup packed light brown sugar; 5 tablespoons cold unsalted butter, cubed; 1 1/4 teaspoons garam masala; Pinch of salt; 1 cup confectioners’ sugar; 2 to 3 tablespoons milk