FILLET OF BEEF WITH PROSCIUTTO IN FOIL

2 tablespoons butter
2 tablespoons chopped shallots
1 cup chopped mushrooms
1 tablespoon brandy
2 tablespoons beef poaching liquid
2 teaspoons chopped parsley
Salt and pepper
2 large, paper-thin slices prosciutto
4 slices (1-inch- thick) rare poached beef fillet

SAUCE:
1 cup beef poaching liquid
1 garlic clove, peeled
1 teaspoon brandy
Salt and pepper
1 teaspoon cornstarch dissolved in 1 tablespoon cold water

Melt butter in heavy skillet; stir in shallots and mushrooms. Saute for 2 minutes; reduce heat and simmer slowly until almost dry. Pour brandy and poaching liquid into pan. Cook over high heat, stirring, until liquid evaporates. Remove from heat. Add parsley and salt and pepper to taste. Transfer to a bowl and let cool. Preheat oven to 425 degrees. Place 2 sheets of foil, each 12 x 16 inches, on a work surface. Butter center area lightly. Lay a slice of prosciutto left of center on each sheet. Spoon 1/4 of mushroom mixture on half of each prosciutto slice. Top each with 2 slices of beef and another 1/4 of mushroom mixture; then fold the other half of the prosciutto on top. Fold foil over meat, like closing a book. Crimp edges tightly together, forming D-shaped packages. Transfer to baking sheet and bake for 6 minutes, just long enough to heat through. Meanwhile, place poaching liquid, garlic and brandy in small pan; boil hard to reduce by half. Discard garlic, and season to taste with salt and pepper. Stir in cornstarch mixture and let bubble until it thickens, about 1 minute. Place foil packages on dinner plates. Slit along straight side and carefully pull away foil. Spoon sauce over meat. Serves 2.