Cook grits in a large Dutch oven according to package directions. Add cheese; stir until cheese melts. Stir in whipping cream, salt, mace, and pepper; cool completely.
Beat eggs lightly; add baking powder, and beat until well blended. Fold egg mixture into grits mixture. Spoon into a lightly greased 3-quart casserole. Bake at 375° for 50 minutes or until golden brown. Let soufflé stand 10 minutes before serving.