Bring a large pot of salted water to a boil. Add the ravioli and cook 4 - 5 minutes until tender, but still firm. Drain ravioli.
Meanwhile, in a medium saucepan, cook the butter over medium heat, stirring occasionally. When the foam subsides, and the butter begins to turn a golden brown, about 3 minutes, turn off the heat. Let cook for about 1 minute. Stir in the balsamic vinegar, salt, and pepper.
Transfer the ravioli to the saucepan with the balsamic butter. Sprinkle walnuts and parmesan over the top. Serve immediately.
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