Cook the rutabagas in 1 inch of boiling salted water for 10 minutes or until very tender.
Drain and put through a ricer.
Return to the saucepan.
Over low heat, stir in the butter, beginning with 4 tablespoons.
Stir in the consomme and season with salt, pepper and mace.
Beat as you would mashed potatoes; if too dry, beat in the remaining butter.
Beat in the sherry.
Cook, beating constantly, for 2 or 3 more minutes.