Preheat the oven to 350°F.

Generously brush olive oil over both sides of baguette slices, then transfer to a baking sheet and bake until lightly toasted, about 10 minutes. Set croutons aside.

Increase oven temperature to 400°F.

Heat 3 tablespoons oil in large ovenproof skillet over medium high heat.

Add onions, 1/4 cup of the parsley, anchovies, thyme,  and red chile flakes and cook until onions begin to soften, about 5 minutes.

Add garlic and cook 1 minute more.

Stir in tomatoes and wine.

Season sea bass with salt and pepper, then arrange fillets in skillet so that the vegetables are on top of the fish.

Bring to a simmer.

Cover, transfer to the oven and bake until fish is opaque in center, about 10 to 12 minutes. Transfer fish to plates.

Stir remaining parsley into sauce in skillet and boil gently until thickened, about 2 minutes.

Season to taste with salt and pepper, then spoon sauce over fish.

Serve with toasted croutons on the side.