Preheat the oven to 350. Lightly grease a 9x13 or slightly smaller baking dish and set aside. I used a 9x11x3 pan when testing.
Cook the pasta according to the package directions adding 1/2 tablespoon of salt to the boiling water, then cook 1 minute less than the package directions for al dente. Drain; leave it in the colander and set aside.
In a 9" or larger skillet, add the avocado oil over medium high heat and add the onion. Saute 3 to 5 minutes then add the beef and sausage and cook, breaking up any large pieces until no pink remains. Add the garlic and chopped rosemary and cook 30 seconds more then drain as much fat as you can from the meat. Set aside.
In a small bowl, mix the sour cream and ricotta cheese together in a small bowl and set aside.
In the baking dish mix the cooked pasta, pasta sauce, and meat mixture. Add the salt and stir well.
Add the sour cream and ricotta in 2 tablespoon dollops around the dish and use a spoon or knife to gently swirl it in to the pasta, but don't mix it in totally.
Add half the mozzarella and half the meunster to the pasta and gently mix it around--don't worry about mixing it in totally.
Add the other half of the cheeses to the top. Lightly grease a sheet of foil or use a layer of parchment paper then foil and cover; bake 10 minutes then uncover and bake 5-7 minutes more; broil the top until golden brown if you have time.
If baking cold from the refrigerator, bake covered 20 to 25 minutes, then uncovered 5 to 10 minutes. Just until the center is hot.