My maternal grandmother's name is Irene and as long as I can remember, we've always called her "Mother Rene" ("Rene" as in "green"). This is her sugar cookie recipe. They are light-as-air wafers of goodness. If you like a denser, teacake-like texture, look elsewhere.
They are a snap to make!
Flattening them before baking makes them even crisper. I think the cream of tartar, vegetable oil, and powdered sugar are somewhat unusual in a sugar cookie recipe - but the end product will literally melt in your mouth.
Mother Rene's Sugar Cookies
Makes 3-5 dozen, depending on size
1/2 cup (1 stick) butter, softened
1/2 cup granulated sugar
1/2 cup powdered sugar
1/2 vegetable oil
1/2 teaspoon vanilla extract
2-1/8 cup all purpose flour
1/2 teaspoon cream of tartar
1/2 teaspoon baking soda
1/4 teaspoon salt
Cream butter with paddle attachment of a mixer. Gradually add sugars, then oil, eggs, and extract. Combine the dry ingredients and slowly add to the butter mixture. Cover and chill dough 2 hours. Shape into 1" balls and place 3" apart on a cookie sheet. Flatten each cookie slightly with the flat bottom of a drinking glass dipped in sugar. Bake at 375 degrees for 5-8 minutes. Do NOT over bake - take them out of the oven before they begin to brown.
Tips: The thinner the cookie (i.e., the more you flatten it out), the crisper it will be in the end.