In a large pot over medium heat, drizzle in a little olive oil and 2 Tbsp butter. Sauté the onion, carrot, celery, and garlic all together with a pinch of salt, pepper, and red pepper flake (if using). Cook until everything is softened, about 10 minutes. Everything for the sauce happens in the same pot!
Add in the ground beef and Italian sausage with another pinch of salt, pepper, and red pepper flake. Break meat up with whatever utensil you're using until it's all evenly browned. MEAT FEST, BABY!
Once meat is perfectly browned and crumbled, pour in heavy cream and nutmeg. Give it a nice stir so everyone in the pot can say hi. Turn the heat up a bit and bring to a boil, then immediately turn the heat down to where it was and simmer until all liquid has evaporated. Do not stir while waiting for evaporation. This takes some time (as does this entire dish), so be patient!
We're gonna do the same thing with our wine. Add it in, stir to mingle, bring to boil, reduce to simmer, and let it evaporate completely. Again, do not stir while waiting for evaporation. It doesn't show yet, but we are building some major flavors here, my people!!!
After the wine has completely cooked out, it's time to add in the whole tomatoes with their juices, and the tomato paste. Remove the whole tomatoes one by one, breaking them up with your fingers, before dropping them in the pot. Careful, they're squirters.
Finally, stir in the thyme, rosemary, and parmesan.
Eventually, the sauce is gonna start to bubble. Reduce heat until the timing between bubbles decreases. This is where we want our sauce to stay, at a lazy simmer.
Keep it here for 2-3 hours, stirring every so often, and tasting for salt and pepper. If the sauce starts to dry out and tighten up, add about ⅓ cup water and stir. This will inevitably happen, and I end up adding water several times throughout the lazy simmer process. This is building major flavor flave.
When ready, toss with cooked, drained pasta and remaining 2 Tablespoons cold butter. When butter has incorporated completely into sauce and everything is heated through, you're ready to enjoy the fruits of your labor and loins.