Cut salmon into 4 pieces, rinse, and pat dry. Set aside. In large skillet, combine water, wine, green onions and bay leaf. Over high heat, bring just to boil. Carefully add salmon and return to boil. Reduce heat, cover and simmer 8 to 10 minutes, or until fish flakes easily with fork.
Remove fish and pat dry with paper towels. Cut each salmon steak in half, removing as much of the bone, cartilage and skin as possible.
Meanwhile, cook spinach according to package directions. Drain well, squeezing out moisture. Stir in nutmeg.
Preheat broiler. Place fish on broiler-proof serving platter or on rack of an unheated broiler pan. Top with spinach mixture, sprinkle with cheese and season with pepper. Broil 4 inches from heat 1 to 2 minutes, or until cheese melts. Garnish with lemon slices, if desired.