Cook 3 minutes per side over medium-high heat, turning once. Remove from skilletand season with salt and pepper as desired. On a flat surface, stack phyllo dough sheets, spraying each sheet thoroughly with cooking spray. Cut stacked layers to make 4 equal squares. Place about 2 Tbsp. of mushroom mixture in center of each phyllo square.
Place steaks on mushroom mixture.
Bring together all 4 corners of phyllo dough. Twist tightly to close. Lightly spray each packet with cooking spray and place on a greased baking sheet. Immediately bake in preheated oven for 9-10 minutes or until golden brown.