Preheat the oven to 350 degrees F.
Set a large, wide-mouthed 6-quart pot over medium heat. Add the olive oil and pancetta to the pot and cook the pancetta until lightly browned, 3 to 4 minutes. Add the onions and garlic to the pan and cook until translucent, 3 to 4 minutes. Add the butter and flour to the pot and cook, stirring, for 3 minutes. Add the half-and-half to the pot and whisk until smooth. Bring to a boil then reduce the heat to a simmer. Season with the salt, white pepper and nutmeg and cook for 3 minutes. Add the pasta to the pot and remove from the heat. Add the grated cheeses to the pot and stir to combine well.
Transfer the contents of the pot to a 3-quart baking dish. In a small bowl, combine the bread crumbs with the Essence and sprinkle over the top of the macaroni. Bake uncovered until golden brown and bubbling, 40 to 45 minutes.
Combine all ingredients thoroughly.
Recipe from "New New Orleans Cooking", by Emeril Lagasse and Jessie Tirsch, published by William Morrow, 1993.