This lasagna is something different and special, most notably because the sauce is made entirely of buttermilk, which works beautifully, making a creamy béchamel with a flavor that hints of butter but without the fat.
If you don’t have your own tomato sauce from the garden, try to buy San Marzano tomatoes in the can — I think they are hands down the most flavorful canned tomato. This dish is surprisingly uncomplicated to put together, despite the fact that I skip the alluring ease of no-cook lasagna noodles and use the traditional kind. The no-cook kind have their place in a busy kitchen, but they lack the robust texture and flavor of old-fashioned lasagna noodles.
To make the sauce, brown the ground beef in a large saucepan over medium heat, 8 to 10 minutes. Spoon off and discard any excess fat.
Add all of the tomatoes, crushing the whole tomatoes with the back of a spoon against the side of the pan, and the wine. Add the onion halves, garlic, butter, and oregano. Bring to a boil and then decrease the heat and simmer, uncovered, for 45 minutes. Season to taste with salt and pepper.
To make the béchamel, melt the butter in a medium saucepan over low heat. Sprinkle in the flour and cook, stirring, just to combine. Pour in the buttermilk gradually, whisking as you go to avoid lumps, and cook until thickened, 3 to 4 minutes, whisking constantly. Remove from the heat and season with salt and pepper to taste. Keep the sauce warm.
Preheat the oven to 350 degrees. To assemble, put a cupful of the tomato sauce in the bottom of a 9 by 13-inch baking dish. Add a layer of noodles, a few spoonfuls of the béchamel, and sprinkle with 1/3 of the Parmesan. Add a layer of noodles, and continue to layer tomato sauce, béchamel, Parmesan, and noodles, until completed. Cover the top layer of noodles with the shredded mozzarella and bake until bubbling and browned, about 30 minutes. Let the lasagna sit for 15 minutes before serving.