Snickerdoodle Cake

Name: Snickerdoodle Cake
Cook time: 1 h 5 min
Total time: 1 h 5 min
Cuisine: American
Ingredients: 12 tablespoons (1 1/2 sticks) unsalted butter, at room temperature, plus more for greasing the pans; 2 1/2 cups all-purpose flour; 2 teaspoons baking powder; 1 teaspoon ground cinnamon; 1/2 teaspoon fine salt; 6 large egg whites; 1 cup whole milk, at room temperature; 1 tablespoon pure vanilla extract; 1 1/2 cups sugar; Pinch cream of tartar; 3/4 cup plus 1 tablespoon sugar; Pinch fine salt; 6 large egg whites; 4 sticks (16 ounces) unsalted butter, cut into 1 1/2-inch chunks, at room temperature; 1 1/2 teaspoons ground cinnamon; 1/2 teaspoon pure vanilla extract