make-ahead mushroom (+ onion) gravy

This is the sibling of make-ahead mushroom gravy. One of my kids said that the original was too mushroom-ey and to please fix it.

So I  did. Added more shallots and a whole onion. As a bonus, taking out the porcini mushrooms and their requisite re-hydrating nearly halves the prep time. I also thought about trading creme fraiche for sour cream, but ultimately kept it because it adds a nice taste and mixes much more smoothly than sour cream. Butter makes it shiny and creamy, so I don't recommend substitutions.

We had this version with salted turkey at our Christmas party this year and it was approved by both the mushroom and non-mushroom constituencies.

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1/2 stick of unsalted butter
3-4 shallots, thinly sliced (rings)
4 cloves of garlic, thinly sliced
1 onion, thinly sliced (rings)
About 6-8 crimini (brown) mushrooms, thinly sliced
  (white would be OK too)
About 6 fresh shiitake mushrooms, stem removed and thinly sliced

1t (or so) chopped fresh thyme (I used lemon thyme)
2t fresh sage
1 cup of vermouth
1 large box of chicken stock
1/2 cup creme fraiche 
5t cornstarch
A little bit of turkey/chicken drippings if you have them

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Melt butter in a big pan and add shallots and garlic. Stir it up for about a minute than add sage, thyme, and whole chopped onion. Cook until soft and onion just starts to brown. Add crimini and shiitake and cook until they are tender and releasing the mushroom juice. Add vermouth, most of the chicken stock (leave about 1/2 cup). Bring this to a soft boil for about 10 minutes. Stir in creme fraiche, and keep stirring.

In a separate bowl, stir in the rest of the chicken stock and the cornstarch. Add this to the gently boiling gravy. Cook until it starts to get thick--about 5 minutes. At the very end, add some turkey drippings if you have them, to your taste. Use a gravy separator to minimize the oil.

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