1. In a large pot of boiling salted water, cook pasta according to package instructions. Add broccoli rabe 2 minutes before pasta is done cooking. Reserve 1/2 cup pasta water and set aside; drain pasta mixture.

2. Add bacon to pasta pot and cook over medium-high until some fat renders, 2 minutes. Add walnuts and cook until nuts are toasted and bacon is lightly browned and crisp, 3 minutes. Add garlic and cook until fragrant, about 1 minute. Add pasta mixture; toss to combine, adding enough pasta water to create a thin sauce that coats pasta. To serve, season with salt and pepper and sprinkle with Parmesan.