Start by making your sauce. Heat 1 tbsp extra virgin olive oil in a large saucepan. When hot add the sausage and cook for 3 minutes until no longer pink, breaking up the meat with a spatula or wooden spoon.
When the sausage is cooked, add the minced onion and garlic and cook for another 2 minutes until the onions become translucent. Add the tomatoes and the chili flakes and simmer for 10-15 minutes while you cook your pasta and broccoli rabe.
Add the penne to a large pot of boiling salted water. Allow it to cook for 5 minutes on its own before adding the chopped broccoli rabe. (Make sure that you’ve washed the broccoli rabe very well…it can have a slightly dirty taste if you slack on this. Gross.) Cook for five more minutes and strain the cooked pasta and broccoli rabe. (The penne should be al dente and the broccoli rabe tender.)
Pour the pasta back into the large pot and add your sauce. Gently toss to coat. Serve immediately. Top with grated Pecorino Romano if you wish.