- Whisk together flour, baking soda, baking powder and salt in a large bowl.
- In another large bowl, with an electric mixer, cream together butter and sugar until light and fluffy. This will take about 4 minutes. Add the eggs, one at a time, beating well after each addition. Add the vanilla and sour cream, mixing on low speed until combined.
- Add the dry ingredients, and beat at low speed until combined. Divide dough into two pieces, and shape into rectangles about 1 1/2 inches thick. Wrap in plastic wrap, and chill for at least 2 hours or overnight.
- Preheat oven to 350 degrees. Roll dough to 1/4-inch thickness. Shape and cut cookies, and place on parchment-lined cookie sheets. Bake 8 to 10 minutes or until cookies are just slightly golden around the edges. Don’t over-bake if you want soft cookies. Transfer cookies to a rack, and let cool. Let cookies cool before frosting.