Prep. Preheat the oven to 375°F and grease a standard muffin pan (12 muffins) thoroughly with butter.
Combine the dry ingredients. In a large mixing bowl, whisk together the flour, baking powder, cream of tartar, and salt.
Combine the wet ingredients. In a separate mixing bowl, whisk together the vegetable oil, sugar, eggs, milk, buttermilk, and vanilla.
Put it all together. Add the wet ingredients to the dry ingredients and mix just until combined. No more. Set aside.
Make the cinnamon sugar topping. Whisk together the sugar and cinnamon.
Assemble. Fill each muffin tin ~3/4 of the way full. Top each muffin with a generous amount of cinnamon sugar.
Bake. Bake for 15-20 minutes or until a toothpick inserted into the center of a muffin comes out clean with a few crumbles.
Notes
If you love cream cheese, you can always mix up a little bit of softened cream cheese, vanilla extract, and some powdered sugar and mix it into the snickerdoodle muffin recipe before you top it with the cinnamon sugar mixture.