Prepare veggies by chopping or grating beforehand; whirl tomatoes in a blender.
Heat butter and oil in a dutch oven or stew pot. When the butter is foaming, toss in the chopped prosciutto and stir over medium high heat for a moment or two until the prosciutto browns a bit and sizzles. Add in the chopped light green onion or scallion stems and the grated carrot and celery. Continue to saute until the vegetables are slightly soft, a few minutes more.
With heat still on medium high, add the meat and let the meat brown on both sides and no longer pink. Then add in the mushrooms and a bit more butter if needed. Then stir in the veggies that you pushed to the side of the pan while browning the meat. If you need to add more oil or butter to help the meat brown, add it one tablespoon at a time.
Now that meat, mushrooms and veggies are all stirred together, stir in the wine, letting the wine bubble up a bit. Add in the parsley, salt and pepper, and nutmeg and cook until the wine cooks down a bit, 3 or 4 minutes.
Whirl the tomatoes in a blender until blended. Pour tomatoes into the pan and stir into the veggie/wine mixture until the mixture comes to a boil. Then turn the heat down to a simmer and simmer half covered on low for 1 hour or until the oil comes to the top of the sauce. While it is simmering check to make sure the sauce is not boiling away. Add 1/2 cup of water at a time to keep up the amount of sauce in the pan, or don't add any if the sauce doesn't seem to be evaporating. When the oil comes to the top, the sauce is done.
Add in the cream, stir it in and let simmer on low a few more minutes making sure the sauce is still at a simmering temperature.Then turn off the sauce and set it aside while you boil your pasta.
I used a GF pasta called egg tagliatelle. When 3 quarts of water came to a boil, I threw in a tbsp of salt and stirred in the pasta, giving it several good stirs. (Make sure the pasta stays immersed in the boiling water.) When the water came back to a boil, I cooked it for 10 minutes, and then poured it into a colander in the sink.I rinsed the pasta with hot water to remove the glueiness that GF pasta has after cooking it. Doing the rinse made the pasta behave and taste much more like non-GF pasta. When I combined it with that wonderful bolognese sauce sprinkle with grated reggiano parmigiano cheese, the dish tasted as good as the non-low fodmap version. Yay!