• Preheat oven to 400°F. Line baking sheet with foil or parchment paper. Brush both sides of mushrooms with 2 tbsp of olive oil; season with salt and pepper. Arrange mushrooms, stem side up, on baking sheet. Roast for about 10 minutes or until slightly tender. Let cool.
• Meanwhile, heat remaining olive oil in large nonstick skillet set over medium-high heat; crumble in sausage and cook for about 5 minutes or until lightly browned. Add onion and garlic; cook for 3 to 5 minutes or until softened.
• Stir in pesto and tomatoes until well combined. Add Swiss chard; cover and cook for about 5 minutes or until wilted. Stir well and remove from heat. Divide mixture evenly among mushroom caps, mounding if necessary. Sprinkle with cheese.
• Roast for 15 to 20 minutes or until mushrooms are tender and cheese is melted. Sprinkle with basil before serving.

Tip: Use the sausage mixture to stuff hollowed-out zucchini or eggplants, or serve over cooked spaghetti squash.