Stuffed Balsamic-Grilled Portobello Mushrooms

Stuffed Balsamic-Grilled Portobello Mushrooms: 3 1/2 Tbsp olive oil, divided,   1 1/2 pints red cherry or grape tomatoes,   1/2 tsp kosher salt, plus more for sprinkling (optional),   1 1/2 tsp freshly ground black pepper, divided,   1 tsp dried thyme,   4 large portobello mushrooms, stems and gills removed,   4 tsp balsamic vinegar,   4 ounces smoked mozzarella, thinly sliced,   1 10-ounce bag baby spinach, steamed.\

Preheat oven to 425°. Drizzle a roasting pan with 1 tablespoon of the olive oil and add tomatoes, 1/2 teaspoon salt, 1/2 teaspoon pepper, and thyme. Toss to mix. Roast for 15–20 minutes, or until tomatoes start to burst. Keep oven hot. Preheat grill or broiler to medium heat. Place mushrooms gill-side up on a work surface and sprinkle with 2 tablespoons olive oil, balsamic vinegar, a little kosher salt (optional), and remaining 1 teaspoon pepper. With remaining 1/2 tablespoon oil, lightly coat the rounded side of the mushroom caps. Place mushrooms, gill-side down, on grill or broiler pan. Grill or broil for 6–8 minutes on each side, until soft and slightly charred. Transfer mushrooms to a roasting pan and fill with 10–15 tomatoes each. Top with cheese. Place in hot oven until cheese bubbles. Set each mushroom on a mound of steamed spinach and serve immediately. Recipe courtesy of Delicious Living.