For the Mushroom Stuffing:
- 8 ounces mixed mushrooms, sliced
- 8 ounces crimini mushrooms, sliced
- 2 cloves garlic, minced
- 2 tablespoons olive oil
- 1 1/2 tablespoons sherry vinegar
- 1/2 teaspoon fresh-squeezed lemon juice
- 3 sprigs fresh thyme
- Kosher salt and black pepper
For the Burgers:
- 1 1/2 pounds ground beef
- 1 1/2 tablespoons grated onion
- 1 tablespoon steak sauce
- 1 teaspoon garlic powder
- 4 slices of Swiss cheese, plus four 1 ½” cubes Swiss cheese
- 1/4 cup cracked black pepper for crusting
- 4 hamburger buns
- Toppings, as desired