Place the salmon fillets in the center of a 12βx18β (30Γ45 cm) sheet of aluminum foil, each. Divide the asparagus into four equal portions and place them around the salmon.
In a bowl, combine the butter, lemon juice, garlic and parsley. Pour over the salmon and asparagus, season with salt and pepper to taste and top with 2 to 3 tablespoons of Parmesan cheese.
Close the aluminum foil and seal the sides tightly, in foil.