Super-Crumb Coffee Cake

Name: Super-Crumb Coffee Cake
Prep time: 20 min
Cook time: 55 min
Total time: 1 h 15 min
Cuisine: American
Ingredients: 1 Tablespoon all-purpose flour, for coating the pan; 2 cups all-purpose flour (spoon & leveled); 1 cup + 2 Tablespoons granulated sugar; 1 teaspoon salt; 10 Tablespoons (1 and 1/4 stick) unsalted butter, firm and cold; 1 teaspoon baking powder; 1/2 teaspoon baking soda; 3/4 cup buttermilk, at room temperature; 1 large egg, at room temperature; 2 teaspoons pure vanilla extract; 2/3 cup packed light or dark brown sugar; 2 teaspoons ground cinnamon