TO PREPARE: Pour polenta on an oiled work surface and spread 1/4" thick. Let stand until cooled completely and firm, about 15 min. Cut into 3" squares; set aside. (Can transfer squares to a baking sheet, cover and refrigerate overnight.) For the sauce: soak dried mushrooms in 1/3 c warm water until softened, about 30 min. Strain liquid through a fine sieve; reserve. Chop mushrooms coarse. TO COOK: Heat oil and butter in a large skillet. Add onions, parsley, carrots, and celery; saute' until softened, about 10 min. Add ground meat; saute' until lightly browned, about 8 min. Stir in mushrooms, reserved mushroom soaking liquid, tomato paste, and wine; simmer for 5 min. Add tomatoes and their reserved juice; partially cover and simmer until sauce thickens slightly, about 30 min. Season this sauce with 1t salt and 1/2 t pepper or to taste. (Can cool, cover, and refrigerate overnight.) Heat oven to 450F. Arrange half of the polenta squares in the bottom of an oiled 13x9" baking pan. Pour half the sauce over the polenta squares; spread to cover. Sprinkle half the grated cheese over the sauce. Repeat with another layer of each. Bake until lasagne is heated through and cheese is golden brown, 15 20 min; let stand 10 min, cut into squares and serve. From Cook's magazine, Nov '89.