Combine egg yolks, sugar, milk, half-and-half, and mace in top of a double boiler; stir with a wire whisk until well blended. Cook over boiling water, stirring constantly with a metal spoon, until mixture is slightly thickened and coats the spoon. Set aside, and keep warm.
Beat egg whites (at room temperature) until foamy. Add powdered sugar, 1 tablespoon at a time, beating until stiff peaks form. Fold in orange rind.
Divide meringue mixture into 8 equal portions, and place in the center of each crêpe. Fold crêpe in half, keeping meringue inside. Place filled crêpes in a buttered 15- x 10- x 1-inch jell y roll pan. Bake at 450° for 5 minutes.
Remove from oven; place each crêpe on a warmed serving dish. Combine reserved sauce and rum, mixing well. Spoon sauce over soufflé, and serve immediately.