01 - In a large bowl, whisk together olive oil, balsamic vinegar, minced garlic, thyme, rosemary, salt, and pepper. Add the mushrooms and toss to coat evenly. Let marinate for 10 minutes while you heat the grill.
02 - Preheat an outdoor grill or grill pan to medium-high heat. Thread the mushrooms onto skewers or place them in a grill basket for easier handling.
03 - Grill the mushrooms for 3–4 minutes per side until tender and nicely marked with grill lines, basting occasionally with any leftover marinade.
04 - Melt the butter in a large skillet over medium heat. Add the grilled mushrooms and sauté for 2–3 minutes, stirring occasionally, until fragrant and lightly browned.
05 - Remove the skillet from heat. Sprinkle with fresh chopped parsley and adjust the seasoning with additional salt and pepper to taste.
06 - Transfer to a serving dish and serve warm. Offer lemon wedges on the side for squeezing over the mushrooms, if desired.