For the Bucatini Pie:
Preheat the oven to 350F. Spray a 9" or 10" springform pan (or deep cake pan) with pan spray. Put a circle of parchment in the bottom of the pan. Set aside.
Bring a large pot of water to a rolling boil. Salt it well and cook the pasta to al dente. While the pasta is cooking, mix up the cheesy goodness.
In a large bowl, evenly and thoroughly combine 1 lb of the mozzarella with the ricotta, Parmesan, Asiago, beaten eggs, milk and seasonings. Fold in the sopressata very well so it is evenly distributed. Set aside.
When the pasta is al dente, drain and run some cold water over it. You don't want to chill it, but you do want to take the edge off of the heat so your eggs don't cook too soon. Drain the pasta very well after rinsing.
Gently but thoroughly stir the bucatini into the cheesy goodness. It will take some doing because the cheese mixture is pretty stodgy. That's okay. Keep at it until everything is nicely combined. Scoop the cheesy pasta into the prepared pan, trying to spread it as evenly as possible. Press it down a bit so there are no big gaps or air pockets. Cover the pan with foil.
Bake in the center of the oven for 40 minutes. Remove the foil and bake an additional 20 minutes. Remove from oven and run a knife around the outside of the pan. Allow to cool about 10-15 minutes and then remove the sides of the pan.
Serve hot or warm, or even at room temperature, with a side of the marinara sauce, which you either made ahead or made while the bucatini pie was in the oven, right?
For the Marinara:
Over medium heat, melt the butter and oil together. When the butter is sputtering, add the garlic. Swirl the pan and watch carefully. You want the garlic to turn a medium golden to dark brown but not burn, so be careful. When it starts to go, it goes fast. When the garlic has some lovely color on it, pour in the tomatoes all at once. Add the salt, pepper and optional pepper flake. Chances are it will taste a little flat at this point, but you'll be reducing this for a long time so under-seasoning is preferred. You can correct at the end if necessary.
Cook the tomatoes, stirring occasionally and breaking up the tomatoes into smaller and smaller chunks, until the sauce is very thick and is starting to stick to the bottom of the pan a bit. It will also darken in color to a deep, intense reddish-orange. This whole process could take 45 minutes or so, so don't rush things. Once the sauce is thick and perfect, taste and adjust the seasonings if necessary.
Serve hot or warm with the bucatini pie, or use it for pretty much whatever you want.