For the noodles: Preheat the oven to 375 degrees F. Cook the pasta in boiling super salty water (like the sea) until just tender, or al dente. Reserve 1/2 cup of the starchy pasta water, and set aside. Strain the pasta from the water. Drizzle a 13-by-9-inch casserole dish with the olive oil.
For the cheese sauce: Melt the butter in a large saucepan over medium-low heat. Whisk in the flour so that it's smooth and pasty, then cook for 2 minutes more, stirring occasionally, so the roux does not stick to the pan. Pour in the milk 1 cup at a time and stir until smooth. Simmer gently, stirring occasionally so there are no lumps and nothing sticks to the bottom and edges of the pan, for 10 minutes. Season with the nutmeg and 1 teaspoon salt. Reserve 1/4 cup of each of the cheeses and set aside. When the bechamel sauce is smooth and velvety, reduce the heat to low and stir in the garlic and remaining 3/4 cup of each of the shredded cheeses. Add the reserved pasta water. Taste and season with additional salt and pepper as desired.
Place the pasta in the prepared casserole dish and toss to lightly coat with the olive oil. Pour the cheese sauce over the pasta and stir well to combine.
Sprinkle the reserved 1/4 cup of each of the cheeses over the pasta. Give the dish a little shake to help settle the sauce.
For the topping: In a small bowl, mix together the cracker crumbs, melted butter and dried herbs. Press the cracker crumbs on top of the pasta. Bake until golden brown and bubbly, 25 to 30 minutes. Serve hot.