Bring a large pot of salted water to a boil. Cook the ravioli according to the package directions, around 5 minutes. Drain and set aside.
Add the olive oil to a medium pan over medium high heat. Add the sliced mushrooms and stir until they begin to brown, about 5 minutes. Add the thyme, sage and a few dashes of salt and pepper. Remove the mushrooms to a plate and set aside. Start on the brown butter sauce.
In a medium saucepan, melt the butter over medium high heat. Stir occasionally about 5 minutes or so. As the butter browns, it will start to foam and turn a deep amber color. As the foam subsides and the butter has a "nutty" aroma, take off the heat and allow to cool for 2 minutes. Add the balsamic vinegar, salt and pepper.
Toss the mushrooms back into the pan with the browned butter sauce and stir. Dish up the ravioli onto individual plates, drizzle with the brown butter pan sauce and top with chopped walnuts and freshly grated parmesan cheese. Serve and enjoy!