Preheat oven to 350 F.
Peel rutabaga and cut into small chunks.
Combine rutabaga, carrots and onion in a heat proof casserole. Sprinkle with brown sugar, ginger, mace, cayenne, and salt. Dot with the butter and pour the broth over the vegetables. Cover and bake in preheated 350 F oven for 2 1/2 hours.
Working in batches, puree vegetables with their liquid in a food processor or blender. Puree until light, but don't let it liquefy. You want a little texture here. Serve immediately, or, if making ahead, reheat, covered, in a 350 F oven for 15 to 20 minutes.
Serves: 4 to 6 as side dish