1 bunch rainbow chard, washed, stems sliced, and leaves torn
The oven to 350 degrees Fahrenheit. In a small pot, melt 4 tablespoons of butter. Add the breadcrumbs, parsley, lemon zest, and half of the shallots to the mixture after seasoning with salt and pepper.
Add salt and pepper to the halibut fillets on both sides. Each fillet should have a thin layer of mayonnaise on top of which the panko mixture should be pressed.
A 12-inch skillet with the final 3 tablespoons of butter should be heated. Add the remaining shallots and rainbow chard stems. After two minutes of cooking, turn off the heat. Add the chard leaves that have been torn, 2 tablespoons of water, and salt and pepper to taste. Over the chard leaves, arrange the halibut fillets.
Until the fish is nearly cooked through for 15 to 20 minutes, place the skillet in the oven.