Creamy Mushroom Sauce
Source: adapted from chow.com
1/2 ounce dried porcini mushrooms (about 1/2 cup)
2 cups boiling water
3 T olive oil, divided
8 ounces fresh cremini mushrooms, stems trimmed and sliced 1/4 inch thick
1 medium onion, chopped*
2 T flour
2 medium garlic cloves, minced*
*can sub shallots for the onion and garlic
Kosher salt
Freshly ground black pepper
1/4 cup dry white wine
1/4 cup heavy cream
Place the porcini mushrooms in a small heatproof bowl, cover with boiling water. Let the mushrooms sit until softened, about 12 minutes. Using a fork, transfer the porcinis to a cutting board (be careful not to disturb the gritty sediment on the bottom of the bowl) and coarsely chop. Transfer to a medium bowl and set aside. Leaving the sediment behind, slowly pour 1 1/2 cups of the soaking liquid into a measuring cup and set aside. Reserve the remaining liquid.
Heat 1 T of the oil in a large frying pan over medium-high heat until shimmering. Add the cremini mushrooms and cook, stirring occasionally, until browned, about 5 minutes. Remove to the bowl with the porcinis.
Reduce the heat to medium, add the remaining oil to the pan, and heat until shimmering. Add the onion (or shallot) and cook, stirring occasionally, until the onion has softened, about 4 minutes.
Sprinkle in the flour and cook, stirring occasionally, until the raw flavor has cooked off, about 1 to 2 minutes. Add the garlic (if using), season with salt and pepper, and cook, about 1 minute.
Add the reserved mushrooms along with any juices in the bowl and stir to combine. Add the wine and cook until almost evaporated, about 3 minutes. Reduce the heat to low, add the 1 1/2 cups mushroom liquid, season with salt and pepper, and cook until the sauce is slightly thickened, scraping up any bits that have accumulated at the bottom of the pan, about 5 to 7 minutes.
Remove the pan from the heat and stir in the cream. Thin with remaining mushroom liquid if needed. Taste and season with salt and pepper as needed.