Meanwhile, cook the butter over medium heat, stirring occasionally. When the foam subsides, and the butter begins to turn a golden brown, like this, turn off the heat. Let cool for about 1 minute. Stir in the balsamic vinegar, salt, and pepper.
Transfer the ravioli to the pan with the balsamic brown butter, fold into the sauce. Sprinkle walnuts and Parmesan over the top. Serve immediately.
*I found this recipe from the Food Network, Giada De Laurentiis, but tweaked it a little by adding less butter and a little more ravioli and walnuts.