Combine first 3 ingredients in a large saucepan. Bring to a boil; stir in grits. Reduce heat, and simmer 3 minutes or until thickened, stirring often. Remove from heat; add butter and pepper, stirring until butter melts. Stir in egg yolks, 1 at a time, and cheese.
Beat egg whites and cream of tartar at high speed with an electric mixer until stiff peaks form. Fold one-third of beaten egg whites into grits; carefully fold in remaining egg whites. Pour into a lightly greased 13" x 9" baking dish. Bake at 425° for 20 minutes or until puffed and browned. Serve immediately.