Boil a large pot of salted water and cook the rigatoni according to package directions until al dente.
Meanwhile, melt the butter in a large skillet over medium heat until it begins to brown and smells nutty.
Add the fresh sage leaves to the butter and fry for 30 seconds until crisp, then remove them and set aside.
Add the onion to the skillet and sauté until soft and translucent.
Stir in the minced garlic and cook for one minute until fragrant.
Whisk in the pumpkin puree, almond milk, vegetable broth, salt, and pepper until the sauce is smooth and simmering.
Add the fresh baby spinach to the sauce and stir until just wilted.
Drain the pasta and toss directly into the skillet with the sauce.
Stir in the Parmesan cheese until melted and fully incorporated.
Garnish with the crispy sage leaves and serve immediately.