Bring a large saucepan of water to the boil and cook the tortellini according to packet directions, LESS 1 minute (so cook for 4 minutes once it has returned to the boil – the pasta will finish cooking in the sauce). Reserve 1 cup of the cooking liquid, then drain the pasta. Set aside.
While the pasta is cooking, add the butter and olive oil to a large frying pan and place over a medium heat. Once butter has melted, add the onion, garlic and bacon. Cook, stirring often, for 5-6 minutes or until the onion has softened and bacon has browned slightly. Add the mushrooms and continue stirring for 1-2 minutes or until wilted.
Add the dijon mustard, cream and French onion soup mix to the onion/bacon mixture, stirring until well combined. Gradually start adding the reserved pasta water, stirring well. (You may not need all of it, I'll let you be the judge – but I did use the whole 1 cup. You can always add more later if too thick).
Add the drained tortellini and stir to combine. Bring to a gentle simmer and cook for 1 minute. Stir through the spring/green onions is using. Serve in bowls garnished with parmesan cheese, extra spring/greens and cracked black pepper if desired. Enjoy.