Heat oil or butter in a nonstick skillet over medium high heat. Add shallots and mushrooms and cook for 3-4 minutes. Season to taste with salt and pepper; set aside.
Bring pot of salted water to a boil, add ravioli and cook for 2-3 minutes, until cooked. Drain, and add directly to skillet with mushrooms and shallots.
Toss ravioli and mushrooms with arugula and grated parmesan. Season to taste with salt and pepper, and option to top with red pepper flakes. Serve immediately.