1 cup (2 sticks) butter, softened
1 1/2 cups white sugar
2 large eggs*, room temperature
3 teaspoons good vanilla extract
2 3/4 cups unbleached all-purpose flour
2 teaspoons cream of tartar
1 teaspoon baking soda**
1 teaspoon cinnamon
To roll the dough in before baking, combine:
3 tablespoons white sugar
4 teaspoons ground cinnamon
Preheat oven to 400 degrees F.
Cream together the butter and the 1 1/2 cups sugar. Add the eggs and the vanilla and beat until soft.
Blend in the flour, cream of tartar, 1 teaspoon of cinnamon, and baking soda.
Shape dough by rounded teaspoonfuls into balls.
Mix the 3 tablespoons sugar and the cinnamon. Roll balls of dough in mixture, and place 2 inches apart on ungreased cookie sheets.
Bake exactly 8 minutes, and as soon as they come out of the oven, sprinkle on a little more of the cinnamon-sugar mixture. Cool for a few minutes on the cookie sheets, and cool completely before storing.
* If your eggs are too big the dough will spread too much. Most recipes call for large eggs - in a recipe calling for 2 eggs, it probably won't matter much, but if you double the recipe it might - 4 extra large eggs are approximately the equivalent of 5 large. If you have extra large and are worried, you can pour off a little of the white (or whisk the eggs first and pour off a little of the mixture). The simplest thing, if you do much baking, is to just always buy large. Here's a conversion chart.
* Baking soda goes flat very quickly, which will give you flat cookies (which are just as delicious, only flat) - here's how to check. Expired or Still Good? The Quickest Way to Test Baking Soda & Baking Powder for Freshness
Easy variations - add nutmeg, cloves, or cardamon to the cinnamon mixture.