Salt
1 pound cavatappi or elbow pasta with lines on conchiglie (small fat tube/shell shaped pasta with lines)
2 tablespoons extra-virgin olive oil
6 tablespoons butter
3 ribs celery with leafy tops, finely chopped
1 medium onion, finely chopped
1/2 small red bell pepper, seeded and finely chopped
3 to 4 cloves garlic, finely chopped
1 bay leaf
About 2 tablespoons freshly chopped thyme leaves, several sprigs
About 1 tablespoon grated lemon zest
Freshly ground black pepper
3/4 pound fresh lump crabmeat, picked for shells and flaked
1 tablespoon seafood seasoning (recommended: Old Bay)
3 tablespoons all-purpose flour
2 1/2 cups milk
Freshly grated nutmeg, to taste
1 tablespoon Dijon mustard
1/3 pound, about 1 rounded cup grated sharp white Cheddar
1/3 pound, about 1 rounded cup shredded Gruyere or Swiss cheese
3 tablespoons hot sauce (recommended: Frank's Red Hot)
1 cup panko bread crumbs
A generous handful flat-leaf parsley, finely chopped
1/2 cup grated Parmigiano-Reggiano cheese, a couple of handfuls