Chop a large handful of roasted, blanched hazelnuts. Heat the butter in a large skillet over medium-low heat until it foams. Add the sage, and cook until the leaves turn crisp, about 1-2 minutes. Remove from heat. Season with salt and pepper.
In the meantime, bring a large pot of salted water to a boil. Cook the ravioli according to package instructions and drain. Return them to the pot, add hazelnuts and garnish with additional sage leaves. Top with Parmigiano Reggiano.