5 tablespoons unsalted butter
4 medium shallots, minced (about 4 tablespoons)
1 pound fresh mushrooms, minced and squeezed dry in cheesecloth
salt and freshly ground pepper
1/4 cup minced fresh parsley
Pinch dried thyme
4 1-1/2-inch-thick médaillons beef fillet or tenderloin (about 6 to 7 ounces each)
Freshly ground pepper
3 tablespoons clarified butter, see note
16 sheets phyllo, approximately 12 b 16 inches each
1/2 pound melted butter, approximately
4 tablespoons fine, dry, white breadcrumbs
1/2 teaspoon salt
4 tablespoons green peppercorns, rinsed in cold water, drained, and crushed
1. To make duxelles, in a large frying pan melt butter. Add shallots and cook gently until soft, about 2 minutes. Add mushrooms and cook until any remaining liquid evaporates and butter is absorbed, about 5 more minutes. Season well with salt, pepper, and nutmeg. Add parsley and time.
2. Pat médallions dry with paper towels and season with pepper.
3. In a frying pan, heat clarified butter (see note) and brown médaillons over medium-high heat just 1 minute on each side. Remove from heat and drain on paper towels.
4. Place 1 sheet of phyllo dough on work surface and brush evenly with melted butter. Place another phyllo sheet on top and brush with more butter. Put 1 tablespoon breadcrumbs in center and place médallion on top. Season with salt and pepper.
5. Press one-quarter of the duxelles on top of médaillon. Sprinkle with one quarter of the green peppercorns, pressing them evenly into duxelles. Wrap médaillon like a package in phyllo dough, folding the ends over the meat. Repeat with another layer of butter phyllo. Place package in center of a fourth sheet of phyllo, which has also been brushed with butter. Draw phyllo up around meat and squeeze together in the middle. Pull the ends up and out to resemble a flower. Make sure all outside surfaces of pastry are brushed with butter. Repeat with other médaillons.
6. Place rosettes in preheated 375ºF oven and bake 15 minutes for medium rare beef. Serve immediately.
Note: To make clarified butter, melt somewhat more butter than needed over very low heat. When completely melted, remove from heat and allow to stand so sediment will sink to bottom of pan. Skim off any surface foam. Pour off clear butterfat from pan into a measuring cup or other receptacle and discard sediment.