Cooking in packets makes for a wonderful moment of revelation: you open the foil (or parchment) wrapper and get a warm puff of fragrant steam to go with your tender fish. Just add more cooking time for a thicker slice of fish.
- 1½ pounds halibut, snapper, or cod fillets, skinned, boned, cut into 5 portions
- Kosher salt and freshly ground pepper
- 2 tablespoons olive oil, divided
- 15 sprigs fresh thyme, divided
- 2 tablespoons chopped toasted hazelnuts
- Flaky sea salt (for serving)
Preheat the oven to 425°. Season fish with salt and pepper.
Cut 5 sheets of aluminum foil, approximately 18 inches long (or, if you are using parchment, fold each sheet of paper and cut it into an angular heart shape).
For each packet (except the lunch portion), place a heaping ¼-cupful of squash compote in the center of the aluminum sheet. Top compote with fish and drizzle with oil. Place 3 sprigs thyme on the fish and seal the packet. The goal is to seal tightly but leave a little airspace around the fish. Bring the long sides together and fold over together, then roll up the short ends neatly. Place the packet on a baking sheet, and repeat with remaining fish fillets. (Top the fifth portion with oil and thyme.)
Bake packets until fish is opaque at the center, 14–16 minutes. Halibut and thicker black cod fillets will take closer to 20 minutes. Reserve packet of fish without compote for tomorrow’s lunch.
Carefully open dinner packets; top with hazelnuts and season with flaky salt.