1. Heat oven to 350°F.
  2. In medium saucepan, bring the water and 1 teaspoon salt to a boil.
  3. Add the cornmeal in a slow stream, whisking.
  4. Whisk in tablespoon of the butter ¼ teaspoon of the sage.
  5. Reduce the heat and simmer, stirring frequently with a wooden spoon, until vey thick, about 20 minutes.
  6. Stir in 3 tablespoons of the parmesan.
  7. Meanwhile, butter an 8"x12" baking dish.
  8. In a large frying pan, melt 1 tablespoon of the butter and 1 tablespoon of the oil over moderately high heat.
  9. Add half the mushrooms, ½ of garlic ¼ tsp each of the salt and sage and ¼ tsp of the pepper.
  10. Cook, stirring frequently until the mushrooms are golden, about 5 minutes.
  11. Remove.
  12. Repeat with remaining mushrooms, salt, garlic, salt, sage and pepper.
  13. Pour half the polenta into the baking dish and spread in an even layer.
  14. Top with half the mushrooms, followed by half of the fontina and 2 tablespoons of the parmesan.
  15. Repeat with remaining polenta, mushrooms, fontina and parmesan.
  16. Bake until cheese is bubbling, about 15 minutes.
  17. Sprinkle with fresh chopped parsley.
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