Heat 2 tablespoons olive oil in a large heavy bottom pot over medium heat. Add in the onions, celery, carrot and a pinch of salt. Sauté until translucent and soft but not browned, about 8 minutes.
Increase the heat to medium-high and add a drizzle more olive oil and the ground Opah. Season with salt and freshly ground pepper and break up any large pieces with the back of a wooden spoon. Cook until the fish is just cooked through and is no longer red, about 4 to 5 minutes.
Add the wine and bay leaf and reduce heat to medium. Cook down until the wine is mostly evaporated.
Add the milk and cook down until it is mostly evaporated. Stir in the ground nutmeg.
Add tomato paste and cook 2 to 3 minutes, stirring frequently.
Add the crushed tomatoes.
When it comes to a simmer, turn the heat down to very low and cook uncovered until the liquid is reduced and the sauce is thick, about 1 to 1 ½ hours. Stir every once in a while.
Taste for seasoning, and add more salt & pepper as needed, then set aside or refrigerate until you are ready to serve.
Before serving, add the sauce to a 12” skillet and warm through. Swirl in 3 tablespoons butter, then add the al dente cooked pasta to the sauce. Stir to combine and cook for about 3 more minutes. If the sauce is too thick, add a little reserved pasta water.
Serve with plenty of freshly grated Parmesan-Reggiano cheese.