Soft Snickerdoodle Cookies

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