In a large sauté pan over moderately high heat, heat butter and allow it to foam and brown but not burn. Slowly sprinkle in flour, and cook at high heat, whisking constantly until a loose paste forms, about 30 seconds. Add shallot, chili, and spices, whisking constantly until the shallot is translucent, about 2 to 3 minutes.
Slowly add milk, clam juice, and oyster liquor, whisking constantly, and bring to a boil. Lower heat to slowly simmer, and cook until the mixture is thickened (and the flour taste is “cooked out”), about 10 minutes. Stir in Swiss chard to heat through. Remove from heat and stir in mascarpone and lime pickle until thoroughly incorporated.
Bread Crumb Ingredients
2 tbsp. salted butter
1 cup panko
¼ cup shredded Asiago (use a Microplane)
Brown butter in pan, toss in bread crumbs (panko) to coat, and let cool. Fold in cheese.
Preheat oven to 400ºF.
Fill a baking pan halfway with rock salt, and heat in oven for about 15 minutes.
Place about 1 or 1½ tablespoons Swiss chard mixture on top of each oyster (depending on size) and sprinkle with about 1 tablespoon panko mix. Transfer to prepared pan and bake until panko is golden brown and slightly bubbling, about 8 minutes.
Line 4 shallow bowls or rimmed serving plates with rock salt mixed with 4 or 5 (each) whole allspice berries and whole clove. Transfer cooked oysters to spiced rock salt and serve.
THE CHEF’S TWIST
Invented at Antoine’s in New Orleans by Jules Alciatore, the original recipe dates back to 1899 and remains a secret. Some speculate it contained spinach, others say watercress, but all agree that the Pernod-laced dish was named “Rockefeller” because it was over-the-top rich and the color of greenbacks. Caswell ends the green debate by using Swiss chard, enriches the sauce with mascarpone (a soft, rich Italian cheese), and replaces the anise flavor of Pernod with the tangy heat of Indian-influenced lime pickle.