This dish can be assembled ahead and refrigerated, covered, for up to 6 hours. If refrigerated, add an additional 10 minutes to the baking time.
Preheat oven to 375°. In small skillet, melt 3 TBS butter and add mushrooms. Saute just until brown and set aside. In saucepan, melt remaining butter over medium-low heat. Add flour, stirring, until thoroughly mixed. Add chicken broth and cream and simmer until slightly thickened. Stir in dry sherry and cheddar cheese until cheese is melted. In medium mixing bowl, combine turkey, sauteed mushrooms and 1 1/3 cup of sauce. Spoon 3-4 TBS of mixture onto each crepe and roll up. Place crepes, seam side down, in greased 11x7x2 inch baking dish. Pour remaining sauce over crepes. Sprinkle with Parmesan cheese. Bake at 375° for 20 minutes, or until warmed through. 6 servings.
Place liquids, eggs and salt into food processor. Add flour and melted butter. Cover and process for one minute. Scrape down sides of work bowl and process for an additional 10 seconds. Refrigerate batter for at least 2 hours.
To cook crepes, heat lightly greased 7 inch skillet over medium high heat, just until it begins to smoke. Remove pan from heat and quickly pour 1/4 cup batter into the pan and tilt to completely cover the pan bottom. Return pan to the heat for one minute. Lift edges of crepe with spatula and quickly turn. Brown second side of crepe for 1/2 minute. Remove to aluminum foil and cool. Crepes can be made ahead and refrigerated or frozen if separated by pieces of waxed paper or plastic wrap. Makes 12-14 crepes.