Preheat your oven to 400°F (200°C) for that perfect flaky texture.
Lightly grease your baking dish with olive oil to prevent sticking.
Pat the Chilean sea bass fillets dry and season both sides with salt and pepper.
Place the seasoned fillets in the baking dish, scatter garlic over the fish, and top with lemon slices and fresh oregano.
Dot the fillets with small pieces of unsalted butter for moisture and richness.
Bake in the preheated oven for about 15-20 minutes, until the fish is opaque and flakes easily.
While the fish is baking, prepare the beurre blanc sauce in a small saucepan.
Carefully remove the fish from the oven, drizzle with beurre blanc sauce, and serve immediately.