Jumbo Popovers

Combine all ingredients; beat at low speed of an electric mixer just until batter is smooth. Fill 12 well-greased 6-ounce custard cups with batter. Bake at 375F for 50 minutes. Quickly cut a small slit in each popover to release steam; bake an additional 5 minutes. Remove popovers from custard cups. Serve warm or cool completely on wire racks.