Cook the pasta according to package instructions for al dente in salted water. Drain, toss with a drizzle of olive oil to prevent it from sticking and return pasta to the pot. \nMeanwhile, while your pasta cooks, heat a large skillet over medium heat and brown the sausage, breaking apart with a wooden spoon, about 5-7 minutes. Remove cooked sausage to a clean plate. Do not wipe out the skillet. \nAdd onion and a drizzle of cooking oil to the pan used to cook the sausage. Cook, stirring occasionally, until softened and translucent, about 5-6 minutes. Stir in the garlic and continue cooking until fragrant, about 1 minute more. \nWhisk in the pumpkin purée, tomato paste and milk until well combined and smooth. Stir in the stock, This Little Goat went to India spice and 1 ½ tsp salt. Bring the mixture to a boil, then reduce to a gentle simmer. Let simmer for about 5 minutes, allowing the flavors to meld and sauce to thicken.\nMix in the sausage, Parmesan and cooked pasta until the pasta is well coated and the cheese has melted into the sauce. Season to taste with salt and pepper. Stir in the arugula and remove from heat. \nTransfer to serving bowls and top with additional Parmesan, if desired. Serve warm.