Preheat oven to 375 degrees. Toss mushrooms, potatoes, onion, and thyme in olive oil, salt & pepper. Spread in a single layer on a baking sheet. Bake for 10 minutes, turn mushrooms and potatoes and bake another 5 minutes or until golden and slightly crispy.

Heat skillet over medium heat. Brush bread slices with butter and truffle oil. Place in pan and top with shredded cheddar, roasted veggies, and more cheddar. Pan grill until golden brown. Top with fresh watercress and freshly cracked black pepper.

Excellent served with a side of tomato veggie soup.