Preheat oven to 350°F. Lightly butter an 8x10” baking dish.
In a bowl, combine the crab, shrimp, brie, mayonnaise, dill, salt, and pepper. Gently blend the mixture together.
Cut a slit along the top of the salmon filets. Divide the stuffing mixture and stuff it into each of the 4 filets. The stuffing will be exposed, mostly sitting on top of the salmon. Place the salmon into the buttered dish.
Bake for 10-12 minutes, until the center of the salmon registers 135° F.
While the fish is cooking, make the sauce. Combine wine, lemon juice, peppercorns, and shallot in a non-corrosive saucepan. Cook over medium heat until the sauce is reduced to about 2 tablespoons, with a syrup consistency, about 5 minutes. Add cream and reduce further until the mixture is about 4 tablespoons and syrupy, about 5 minutes. Remove from heat.
Add the butter, 2 ounces at a time, stirring constantly. Allow each piece to melt before adding more.
When the salmon is done, remove from oven. Serve with the lemon butter sauce spooned over the top.