Directions:

1. Gather all ingredients.
2. Place mushroom caps, smooth side up, in a shallow dish.
3. Whisk together balsamic, oil, garlic, basil, and oregano in a small bowl. Season with salt and pepper.
4. Pour vinaigrette over mushrooms. Let stand at room temperature for 15 minutes or so, turning twice. Preheat grill for medium-high heat.
5. Brush grill grates with oil. Place mushrooms on grill, reserving marinade for basting.
6. Grill until just tender, 5 to 8 minutes per side, brushing with marinade frequently.
7. Top mushrooms with cheese.
8. Continue grilling until cheese is melted, about 2 minutes.
9. Serve and enjoy with your choice of toppings.