Brown the meats: Heat a large heavy-bottomed pot or Dutch oven over medium-high heat. Add 1 pounds ground beef and 1 pounds Italian sausage and brown together, press it down initially so it develops a crust, then break it up as it cooks, until no pink remains (about 15 minutes).Once browned, remove the sausage and beef into a bowl and set aside.
Sauté onions: Add 2 medium onions, diced to the pot. Stir to coat with the fond and let the onions soak it all up. Sauté for about 10 minutes, stirring occasionally, until soft and beginning to caramelize. If the pan dries out too much, add 0.5 cups chicken stock to keep things moist. Also now's the time to add in all the spices you set aside for this dish.
Add garlic: Add 4 garlic cloves, minced and cook, stirring, until fragrant (about 1 minute).
Return sausage and beef and simmer: Return the sausage/beef to the pot with the onions, and garlic. Cook for a few minutes to warm through, then add 2 jar jarred pasta sauces (marinara, arrabbiata, or basil garlic). Stir well to combine.
Slow simmer: Reduce heat to low and let the sauce simmer gently for about 45 minutes, stirring occasionally. Longer simmer builds deeper flavor.
Cook pasta: While the sauce simmers, bring a large pot of salted water to a boil. Cook 1 package pasta (any shape except orzo) according to package directions until al dente. Drain and set aside.
Finish with yogurt: Stir 1 cups Greek yogurt into the sauce until fully incorporated and creamy.(optional)
Combine and serve: Add the cooked pasta directly to the meat sauce, toss to coat, and serve after its been simmering about 5 minutes. Finish with extra fresh basil and parsley if desired.