I must aver that the salmon was FABULOUS and has contributed in no small way to my feeling on the road to recovery tonight. But I should add that I include about 1/2 cup chicken stock in the sauce, added at the same time you want to whisk in the creme fraiche and cream.
Here's a question: you may find that in baking, the sauce splits ever so slightly, at the edges of the serving dish. By split, I should clarify that I mean a slight granulation of the texture, not so severe that one would call it curdling, but a slight not-perfect texture (does not affect the sublime flavor). I think we could bake the salmon on its own and pour the sauce over it from the skillet, when serving, but would that lessen the delightful moist-ness of the salmon itself? It would surely lessen the infusion of brandy and cream into the fish, which produces a delicate but pervasive flavor. Try it, do, and let me know.