Preheat the oven to 425°F and line a baking sheet with parchment paper.
In a shallow bowl, combine the panko breadcrumbs, parmesan cheese, garlic, parsley, basil, thyme, chili flakes, salt, and pepper.
Pour the melted butter into a separate bowl.
Dip each halibut fillet into the melted butter, coating both sides.
Press the fillets into the breadcrumb mixture until evenly coated.
Arrange the Parmesan Garlic Butter Crusted Halibut fillets on the prepared baking sheet.
Drizzle any remaining butter over the fish.
Bake for 15–20 minutes until the crust is golden brown and the fish flakes easily with a fork.
Finish with fresh lemon juice, extra parmesan cheese, and flaky salt before serving.