The Best EVER Sugar Cookie

This is the BEST sugar cookie recipe that I have ever tried...and trust me I have tried many!
I can't even tell you where the recipe came from. It's on a hand written index card that has been inside my recipe file for many years so who knows where I originally got it.

The Best Ever Sugar Cookies (Makes 3 dozen)

1/2 cup butter
1 cup sugar
1/2 cup vegetable oil
1 egg
1/8 tsp. salt
1 tsp. vanilla
2 1/2 cups flour
1 tsp. cream of tartar
1 tsp. baking soda

Cream butter and sugar.
Add oil, egg and vanilla.
Combine remaining dry ingredients in a bowl and then add to the butter mixture.
Form into 1-inch ball (or be lazy, like me, and drop by tbsp.) and place on a greased baking sheet.
Bake 8-10 minutes at 350 degrees.
Cool and then frost with icing.

Icing:
1/4 cup milk
2 tbsp. butter, melted
1/4 tsp. butter flavored extract (or 1 tsp. vanilla)
2 1/2 cups powdered sugar
Food coloring is optional if you want colored frosting
Mix all ingredients together and then frost cookies.
Top with sprinkles.

I have been baking cookies all week long. So many that I could care less if I ever make cookies again. 
Here's a picture of all the different kinds that I made.
(Some of the cookies have a clickable link that will take you to the recipe. Just scroll over them and click!)

There are Peanut Butter Balls, Peanut Butter Fudge, peanut butter cookies with Hershey kisses, Heath Bar Biscotti, and Chewy Noels in the first pan.

Second pan consists of Yuletide Cherry Cookies, Chocolate Chip, Chocolate Heath Chip, Self Frosting Oatmeal, Carmen's Holiday Balls, Buttery Spritz and the Sugar cookies in the center.

Do you have a few favorite cookies that must be made each year at Christmas?