Put the pasta water on to boil. When it comes to a boil, salt the water and cook the pasta according to package directions – stopping just short of al dente.
Meanwhile, make the red sauce. Heat olive oil in a medium sauce pan over medium heat and add the garlic. Cook about a minute until fragrant (don’t let it brown). Add the tomatoes/tomato sauce and simmer for 10 minutes. Stir in the basil and simmer another 10 minutes.
Once the red sauce is simmering make the béchamel sauce. Melt the butter in a small sauce pan over medium heat. Whisk in the flour and cook for about a minute, adding a pinch of salt, a generous grind of black pepper and grating of fresh nutmeg. Whisk in the half and half and bring to a bubble. Reduce for about 5 minutes until the sauce thickens.
Preheat the broiler to high.
Drain pasta and transfer to a 9 x 13 baking dish. Pour the red sauce over the pasta and turn to coat. Pour the béchamel over the pasta and gently push the pasta around to allow to coat the entire top and start seeping down – don’t completely turn the pasta. Sprinkle with the grated parmigano reggiano and top with the sliced mozzarella.
Broil until the cheese is brown and bubble, about 5 minutes. Serve immediately.