The most extraordinary moist Snickerdoodle Cake made by preheating oven to 350°F greasing and flouring two 9-inch pans mixing 1/3 cup sugar and 1 1/2 tsp cinnamon for swirl setting aside whisking 3 cups flour 2 tsp baking powder 1 tsp cream of tartar and 1/2 tsp salt beating 1 cup softened butter and 2 cups sugar 3 minutes light and fluffy adding 4 room temperature eggs one at a time mixing thoroughly then vanilla on low alternating flour mixture and 1 cup milk in three additions beginning and ending with flour pouring half batter into first pan sprinkling generously with half cinnamon sugar dividing remaining batter between pans topping with remaining cinnamon sugar baking 28 to 32 minutes until toothpick clean cooling 10 minutes then on racks then beating 16 oz room temperature cream cheese and 1/2 cup room temperature butter smooth adding 4 to 5 cups sifted powdered sugar vanilla and salt beating fluffy assembling with layers cinnamon-side down and frosting exterior. A completely perfect cinnamon sugar cream of tartar snickerdoodle cake recipe.