From 10-ounce bag fresh spinach, cut 2 leaves in strips for garnish. Steam remainder 4 minutes. When cool, squeeze dry. Chop; mix with seasoned bread crumbs and feta, crumbled. Lay sole fillets on clean surface. Season with salt and pepper.
Place spinach mixture in center of each fillet; roll up. Place butter, in small pieces, in bottom of 12 x 8 x 2-inch casserole. Place sole, seam side down, in casserole. Sprinkle butter, in small pieces, over top. Cover with foil. Bake in 350°F oven for 25 minutes or until cooked through. Garnish with spinach strips. Serve with orzo or rice.