Soft Snickerdoodle Cookies

On Christmas, the first thing my brother in law asked me when I when I walked into the door was where the snickerdoodles were. My brother in law is the pickiest of all the family eaters. When he was a baby, my mother in law claims that he would only eat chicken fingers, grilled cheese, and french fries.
I've tried several recipes for snickerdoodles, and this is the best one that I found so far. They remind me of the packaged snickerdoodles that my mother in law always would buy, except more delicious.

Ingredients
1 cup butter
1 1/2 cups sugar
2 large eggs
2 3/4 cups flour
2 teaspoons cream of tartar
1 teaspoon baking soda
1/4 teaspoon salt
3 tablespoons sugar
3 teaspoons cinnamon

Instructions
1. Preheat oven to 350°F.
2. Mix butter, 1 1/2 cups sugar and eggs thoroughly in a large bowl.
3. Combine flour, cream of tartar, baking soda and salt in a separate bowl.
4. Blend dry ingredients into butter mixture.
5. Chill dough, and chill an ungreased cookie sheet for about 10-15 minutes in the fridge.
6. Meanwhile, mix 3 tablespoons sugar, and 3 teaspoons cinnamon in a small bowl.
7. Scoop 1 inch globs of dough into the sugar/ cinnamon mixture.
8. Coat by gently rolling balls of dough in the sugar mixture.
9. Place on chilled ungreased cookie sheet, and bake 10 minutes.
10. Allow to cool on pan for 5 minutes and transfer cookies to cooking rack.

Source: Juju Bee on Food.com