Pat the Chilean sea bass dry with paper towels and season both sides generously with salt and pepper. In a large skillet, heat 2 tablespoons of extra virgin olive oil over medium-high heat until shimmering. Carefully place the fish skin-side down in the hot skillet and cook undisturbed for 5-7 minutes.

Gently flip the sea bass using a metal spatula, and cook for an additional 5-7 minutes. Keep an eye on the internal temperature, aiming for 145ºF. Once cooked, transfer the fillets to a plate and tent with foil to keep warm while you prepare the sauce.

In the same skillet, reduce the heat to medium and add 2 tablespoons of butter, along with the diced shallots and minced garlic. Sauté for about 1 minute until fragrant and shallots become translucent.

Toss in the halved cherry tomatoes and the Castelvetrano olives into the skillet. Cook for approximately 5 minutes, allowing the tomatoes to blister and soften while mingling with the buttery mixture.

Stir in the fresh lemon juice and torn basil leaves, and sauté for an additional minute. Turn off the heat to preserve the fresh flavors.

Arrange the crispy skin-up sea bass fillets on a large platter, spoon the sautéed tomatoes and olives around the fish, and garnish with additional basil leaves.