2 dozen large white mushrooms, cleaned and de-stemmed (keep stems!)
1 medium yellow onion, diced
1 clove garlic, minced
1 1/2 pound pork sausage (not in casings)
3/4 cup finely chopped walnuts
1 tsp dried sage
1 tsp dried thyme
1/2 tsp kosher salt
3 tsp White Truffle & Garlic Olive Oil
Slice the tough ends off of mushroom stems and discard. Dice the remainder of the stems and set aside.
Heat 1-2 tablespoons olive oil in a large skillet set over medium heat. Add onions and garlic and sauté for about 3 minutes. Add sausage to the pan, stirring to break the meat up into crumbles, until cooked through. Add diced mushroom stems to the pan, along with walnuts, spices and salt. Sauté 5 minutes. Spoon mixture into a bowl and let cool slightly.
Heat oven to 350 degrees. Cover a large baking sheet with parchment paper or aluminum foil, and arrange mushroom caps face-down. Spoon sausage filling into each one of the caps, using the bottom of the spoon to gently press the filling down into the mushrooms. If you want, drizzle the stuffed mushrooms with the truffle oil before putting them into the oven. Bake for 25 minutes.