Place dried porcini mushrooms in a spice grinder and pulse until a powder forms, set aside.
Melt ghee in a large skillet, sauté shallots until they start to brown, about 6 minutes. Add garlic, stirring 1 minute.
Add mushrooms, sauté for 10 minutes, until they release their water and it is almost evaporated.
Add thyme leaves and porcini powder, stir to coat the mushrooms.
Add wine, simmer until reduced by ⅔.
Add chestnuts and almond milk, cook until chestnuts are warmed through and sauces thickens. Season to taste with salt and pepper.
Garnish with additional thyme leaves, if desired
Notes
To make ahead of time, follow directions without adding almond milk. Reheat on the stovetop and add the almond milk at the end. See the blog post for additional details.