4 1/2 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon cream of tartar 1 cup butter, softened 1 cup vegetable oil 1 cup sugar 1 cup confectioners sugar 2 large eggs, room temperature 1 teaspoon vanilla extract Pre-heat oven to 375°F and line a baking sheet with parchment paper. In a large bowl, whisk together the flour, baking soda, and cream of tartar. Set aside. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, oil, and sugars on medium-high speed until light and fluffy, scraping the sides as necessary. Reduce speed to medium and add the eggs, one at a time, mixing just until combined. Add the vanilla and mix until combined. Reduce speed to low and add the flour in three additions, scraping down the sides as necessary. Drop dough of two tablespoon each onto the baking sheet, spacing two inches apart. Bake for 8 to 10 minutes, just until the edges begin to darken. Let cool on baking sheet.