Heavily coat 2 popover pan cups or 2 muffin pan cups with cooking spray, and set aside.
Combine flour and remaining ingredients in a medium bowl; stir with a wire whisk until smooth. Pour batter evenly into prepared pan. Place in a cold oven. Turn oven on 450°, and bake 15 minutes. Reduce heat to 350°, and bake an additional 40 minutes or until popovers are crusty and brown. Serve immediately.