01 - Preheat the oven to 400°F. Line a baking dish with parchment paper or lightly grease it.
02 - Combine olive oil, lemon juice, lemon zest, minced garlic, thyme, salt, and black pepper in a small bowl; whisk until blended.
03 - Pat halibut fillets dry with paper towels and arrange them evenly in the prepared baking dish.
04 - Brush marinade evenly over each fillet and place two thin lemon slices atop each piece.
05 - Bake in the preheated oven for 15 to 18 minutes, or until the fish is opaque and flakes easily with a fork.
06 - Remove from oven, sprinkle with fresh parsley, and serve immediately.