In a saucepan, heat olive oil over medium high heat, add onion and sauté until soft. Add garlic, mushrooms, green pepper and cherry tomatoes, sauté until soft, then add Sriracha and pesto, stirring to combine. Next, add spinach and heat just until wilted, stir in heavy cream and Parmesan, heat through and serve over hot linguini noodles. Top with additional Parmesan if desired