Preheat the oven to 400°F (200°C). This temperature is hot enough to finish the fish quickly without drying it out and will help the tomatoes blister while the cod cooks.

Bring a medium pot of salted water to a rolling boil (use about 1½ teaspoons salt per liter). Salted water seasons the orzo from the inside. Add the orzo and cook 1–2 minutes less than the package's al dente time (usually 6–7 minutes total for orzo) — you want it slightly undercooked because it will finish in the oven and absorb the tomato juices.

While the orzo cooks, heat 2 tablespoons of olive oil in a large ovenproof skillet or sauté pan over medium-high heat. Add the garlic and sauté 20–30 seconds until fragrant — do this briefly so the garlic softens and flavors the oil but does not burn (burnt garlic becomes bitter).

Add the cherry tomatoes (whole if small, halved if larger) and a generous pinch of salt. Cook, stirring occasionally, until the skins blister and the tomatoes begin to collapse, 6–8 minutes. Blistering concentrates the tomatoes’ sweetness and releases juices that will flavor the orzo.

Stir in the Kalamata olives and capers (if using) and cook 1 minute to warm them. Add the lemon juice and about half the lemon zest now — the acid brightens the tomato-olive mixture and balances the briny notes.

Drain the orzo, reserving 1/2 cup (120 ml) of the pasta cooking water. Return the orzo to the pot and toss briefly with 1 tablespoon of olive oil to keep grains separate. Keeping some reserved pasta water lets you loosen the mixture later if it needs moisture.

Add the cooked orzo to the skillet with the tomato-olive mixture and toss to combine over low heat. If the pan looks dry, add 2–3 tablespoons of reserved pasta water — the starchy water helps bind the orzo and tomato juices into a silky bed for the fish.

Push the orzo mixture into an even layer and make four shallow wells. Pat the cod fillets dry with paper towels (drying helps achieve a lightly seared surface). Season both sides of the cod with salt, pepper and the remaining lemon zest.

Drizzle the remaining 1 tablespoon of olive oil over the cod fillets (this promotes gentle browning) and place each fillet into a well on top of the orzo. Dot the fillets with the optional tablespoon of butter for an extra silky finish.

Transfer the skillet to the preheated oven and bake until the cod is opaque and flakes easily with a fork, 10–12 minutes depending on thickness. Baking the fish on top of the orzo lets the steaming juices flavor the pasta while avoiding overcooking the orzo.

Remove the skillet from the oven. Spoon some of the tomato-olive juices from the edges over the cod. Sprinkle chopped parsley on top and finish with a drizzle of extra-virgin olive oil and a squeeze of fresh lemon juice to brighten the dish. Taste and adjust salt and pepper.

Serve family-style straight from the skillet or transfer to a warm platter. The contrast of silky orzo, bright tomatoes and flaky cod is at its best hot and just baked.