Preheat oven to 375 degrees F. Line a baking sheet with parchment paper.

Combine flour, cream of tartar, baking soda, and salt in a medium bowl; set aside.

Beat the butter for 30 seconds. Add both sugars and beat until light and fluffy. Add the egg and vanilla extract and beat well.

Gradually add the flour mixture to the butter mixture until blended. *If dough appears slightly crumbly, add 1 teaspoon of milk. Stir in the Peanut Butter Cheerios and mini chocolate chips.

Using a cookie scoop (or tablespoon), drop dough on cookie sheet 2 inches apart. Bake for 10-12 minutes, until the edges are golden. Remove from the oven and let cool on the pan for 2 minutes. Transfer to a cooling rack to cool completely.