Put Italian sausage (taken OUT of the casings), butter and vegetable oil into a large stockpot (or skillet). Heat on medium heat, stirring often, until butter has melted. Add chopped onions and celery to the pot. Cook for a few minutes, stirring often, until the sausage has fully cooked, and veggies have softened.
Add chopped red bell pepper and minced garlic. Cook, stirring often, for two minutes. Add SLICED mushrooms; cook for 1 more minute, stirring as they cook. You are slowly adding in layers of flavor! Add CHOPPED mushrooms, and cook for 1 minute. Add red wine to pan. Heat, and let wine gently boil for 2 minutes. Add canned tomatoes, tomato paste, beef stock (or vegetable stock), and spices. Stir, to combine all ingredients.
Bring sauce to a boil. Once sauce is boiling, add dry rigatoni noodles; stir to combine. Put a lid on the pan (or cover with aluminum foil); turn heat down to LOW. Let pasta cook for 13-15 minutes (mine took 15), or until pasta is cooked all the way through. Give pasta a stir a few times while it is cooking, then put lid back on pan. If at any time, the rigatoni sausage mushroom ragu looks like it's getting too dry (if heat was too high), add several spoonfuls of hot water to pan, and stir in, to combine.
When the rigatoni sausage mushroom ragu is fully cooked, it's time to serve! Give the pasta a stir, then portion it out into serving bowls. Bowls seem to hold the sauce better than on a plate. Garnish top of each bowl of pasta with some roughly chopped flat leaf parsley and grated Parmesan cheese. Serve... and enjoy!
Rigatoni Sausage Mushroom Ragu https://www.thegratefulgirlcooks.com/rigatoni-sausage-mushroom-ragu/