Cut the mushroom stalks even with the caps and slice 1/8-inch thick
Heat the butter in a 12-inch stainless steel sauté pan; add the mushrooms, and sauté on high heat, tossing all the time, until light golden brown.
Add the fish stock, wine, and salmon, skin side up. Cover and gently simmer for 7 to 10 minutes until the salmon is cooked through. To check if it is ready, insert a small sharp knife into the thickest part of each fillet to check if it is cooked through. Be careful not to over-cook or the salmon will be dry.
Remove the salmon from the pan with a slotted spatula and remove and discard the skin. Keep the fillets warm
On a high heat, reduce the pan juices to a light syrupy consistency. Add the cream and shredded basil and continue to reduce until the mixture is thick enough to coat a spoon. Add any juices that have accumulated from the salmon and continue to reduce for a minute more. Add salt and freshly ground pepper to taste.
Arrange the salmon on four dinner plates and spoon the sauce on top. Garnish each fillet with a basil leaf.