Follow the steps in order for the best result.
Begin by preparing the mushroom marinade. In a large resealable bag, combine the quartered cremini mushrooms with olive oil, balsamic vinegar, honey, fresh thyme, dried rosemary, ground black pepper, and kosher salt. Seal the bag tightly, removing excess air, and toss well to ensure the mushrooms are thoroughly coated with the marinade. For optimal flavor, allow the mushrooms to marinate for 1-2 hours, or longer if desired. If short on time, you can proceed directly to roasting after tossing.
Preheat your oven to 425°F (220°C). Take a large sheet of aluminum foil and place the marinated mushrooms in the center.
Fold the aluminum foil around the mushrooms to create a sealed pouch, ensuring the edges are tightly closed to prevent steam from escaping.
Place the foil pouch on the middle rack of the preheated oven and bake for approximately 20-30 minutes, or until the mushrooms are tender and slightly caramelized. Alternatively, you can cook this dish on an outdoor grill. If grilling, be cautious when moving the pouch to prevent burning. Use a spatula instead of tongs to avoid puncturing the foil.
Carefully open the foil pouch (steam will release) and transfer the honey balsamic roasted mushrooms to a serving dish. Serve immediately and enjoy as a side dish.