Step 1
Bring a large pot of water to a boil for the pasta. Salt the water and add the pasta. Cook until 1 minute shy of the package directions. Scoop out about 3/4 cup of the pasta cooking water, then drain the pasta.
Step 2
Meanwhile, preheat the oven to 350° or heat a skillet over medium. In the oven on a baking sheet or in the skillet, toast the nuts, stirring often, until golden and fragrant, about 5 minutes. Chop the nuts.
Step 3
In a large skillet, heat the oil, two turns of the pan, over medium. Add the garlic. Swirl until aromatic, about 1 minute. Add the escarole; season with salt, pepper, and nutmeg. Toss until the escarole is wilted, about 2 minutes. Mix in the lemon juice. Reduce heat to low.
Step 4
For the sauce, in a small saucepan, heat the milk over medium. Add the Gorgonzola and sage. Stir until the cheese melts into the milk, about 4 minutes.
Step 5
In a large bowl, mix the pasta, sauce, escarole, and Parm; season. Top with the walnuts.