Mushrooms duxelle is just a fancy French term that refers to sautéeing finely chopped mushrooms, onions, and herbs for a long time until they form a paste-like texture. The creamy mushrooms are delicious when spread over crusty bread. But an even better use is to add some sour cream and make a sumptuous gravy to pour over a warm, buttery biscuit.
The mushrooms in this recipe aren't cooked into a paste as you would for a classic duxelle; instead they are coarsely chopped and cooked just enough to maintain some of their toothsome texture, leaving you with something hearty to sink your teeth into. Keep a fork and knife handy for this recipe — like most meals of biscuits and gravy, it's going to get messy!
Vegetarian Biscuit and Gravy Sandwiches
For the mushrooms:
10 ounces brown or cremini mushrooms, tough stems removed, coarsely chopped
2 tablespoons butter, plus more for buttering the biscuits
1 medium shallot, minced
1 teaspoon chopped fresh thyme leaves
1/2 teaspoon fine salt
1/4 teaspoon freshly ground black pepper
1/2 cup sour cream
For the sandwiches:
1/4 cup shredded Gruyère cheese
1 cup arugula
For the mushrooms: Place the mushrooms in the bowl of a food processor fitted with the blade attachment. Pulse until all the mushrooms are finely chopped but not puréed. (You might have to scrape down the sides of the bowl occasionally to re-distribute bigger pieces of mushroom.) Alternatively, you can finely chop the mushrooms by hand.
Melt the 2 tablespoons butter in a large skillet over medium heat. Add the shallot and sauté until translucent and fragrant, about 1 minute. Add the mushrooms, thyme, salt, and pepper. Cook, stirring often, until the mushrooms have softened and released their liquid, about 4 minutes.
Add the sour cream, increase the heat to medium-high, and simmer until some of the liquid is evaporated, 1 to 2 minutes. Take the pan off the heat and reserve.
For the sandwiches: Heat the broiler to high. Lightly butter the cut sides of the biscuits. Place the biscuit bottoms cut-side up on a foil-lined baking sheet. Top the biscuit bottoms with equal amounts of the mushroom gravy and Gruyère. Broil until the cheese is melted, 45 seconds to 1 minute, depending on your broiler.
Transfer the biscuit bottoms to 4 plates. Divide the arugula over the biscuit bottoms and close each sandwich with a biscuit top.