Totally go for getting some vinegar into that sauce and I'd deglaze the pan with some merlot before doing the sauce. And a creamed spinach would then sit better on the plate I would suggest rather than one which is done with olive oil. Nutmeg - totally. Just so as you know it is in there and it isn't terribly noticeable, it will add depth to the flavor. Here's a cut and paste for creamed spinach if you fancy trying it, although with dauphinoise it might be cream overkill. I'd probably use shallots instead of onion here. I'm sure whatever you do it'll be excellent.
Butter 5 T, Flour, plain1/4 C, Salt1/4 t, Black Pepper1/4 t, Nutmeg dash, Half and half 1 C, Cream Cheese 4 oz, Onion, small, minced, Chopped spinach 1 1/4 #, Water1/4 C
METHOD:In a large frying pan saute the onion in 2T of the butter until transparent. Stir in thespinach and water. Reduce the heat to medium low, cover and simmer for about 8 mins.In a saucepan, melt the remaining 3T of the butter and stir in the flour, salt, pepper and nutmeg. Slowly whisk in the cream then slowly stir in the cream cheese.Combine. After reheating mix in three good shavings of parmesan to finish.Check seasoning.