Bake for 8 to 10 minutes or until set but not too browned.
In a large bowl, mix 1 1/2 cups of sugar, butter, shortening, and eggs until smooth.
In a small bowl, mix 1/4 cup sugar and cinnamon.
Place the cookies 2 inches apart on the baking sheets.
Preheat the oven to 375°F (190°C). Line two baking sheets with parchment paper.
Remove from the oven and let them cool for a few minutes.
Roll dough into 1 1/4-inch balls, then roll the balls in the cinnamon-sugar mixture.
Stir in the flour, cream of tartar, baking soda, and salt until combined.
Enjoy these deliciously soft and chewy snickerdoodles, perfect for any occasion!