Cannellini beans, canned or cooked, drained, rinsed, chilled 3 cups
Bread crumbs, toasted ½ cup
Cayenne ¼ tsp.
Kosher salt ½ tsp.
Preheat the oven to 350° F.
For the base: Saute the onions, shallot, and garlic and bay leaf 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 milk to the pot and whisk until smooth. Bring to a boil then reduce the heat to a simmer. Season with the white pepper, nutmeg, and thyme and cook for 3 minutes. Add the grated cheeses to the pot and stir to combine well. Add the pasta to the pot and remove from the heat.
Add the chilled beans and fold them in gently.
Transfer the contents of the pot to a 3-quart baking dish or individual ramekins. In a small bowl, combine the bread crumbs with the cayenne and salt and sprinkle over the top of the macaroni. Bake uncovered until golden brown and bubbling, about 30 minutes.