Prepare the dip ahead of time, and chill; broil just before serving.
Combine 1/4 cup boiling water and porcini mushrooms in a bowl; let stand 10 minutes. Strain porcini mushrooms through a sieve over a bowl, reserving liquid. Chop mushrooms; set aside.
Heat butter and oil in a large nonstick skillet over medium heat. Add shallots, thyme, rosemary, salt, pepper, and garlic; sauté 2 minutes. Stir in reserved porcini mushrooms, wild mushrooms, and cremini mushrooms. Cook 10 minutes or until liquid almost evaporates, stirring frequently. Stir in sherry and reserved mushroom liquid, scraping pan to loosen browned bits. Cook 5 minutes or until the liquid almost evaporates. Remove from heat. Place mushroom mixture and 3 tablespoons cheese in a food processor; process until smooth. Scrape the mushroom mixture into an 8-inch square baking dish coated with cooking spray. Sprinkle evenly with remaining 3 tablespoons cheese. Broil for 7 minutes or until edges of cheese begin to brown. Remove from heat, and sprinkle with parsley.