Icebox Cookies

Ingredients (9)

• 1/2 cup butter, softened
• 1 cup packed brown sugar
• 1 large egg, beaten, room temperature
• 1/2 teaspoon vanilla extract
• 2 cups all-purpose flour
• 1/2 teaspoon baking soda
• 1/2 teaspoon cream of tartar
• 1/2 teaspoon salt
• 1 cup chopped walnuts, optional