Preheat oven to 400° F. Place the butternut squash and shallots into a large bowl and add in the olive oil, Italian seasoning, garlic powder, Calabrian chili paste, salt and pepper. Toss everything together until it’s coated and then dump it onto a baking sheet sprayed with cooking spray. 

Spread the vegetables out into a single layer and roast for 15 minutes, then remove from the oven and toss the squash with a spatula. Return the baking sheet to the oven and roast for another 10-15 minutes or until tender. 

While the squash roasts, bring the pasta to a boil in a large pot of salted water and cook until al dente. Before draining the pasta, ladle out 1 cup of the pasta water.

Combine the ricotta, lemon zest and juice, salt and pepper in the bowl of a food processor and process until smooth. You can also use a blender or whisk it by hand, although it won’t be as creamy when done by hand.

Add the drained pasta back into the pot along with the ricotta. Pour in about 1/3 cup of the reserved pasta water. Stir together until the sauce is coating all of the pasta. If the sauce looks too thick, add in additional pasta water. Taste for seasoning. 

Pour the pasta into a serving bowl and top it with the roasted butternut squash and shallots, chopped walnuts, and Parmesan cheese.