Preheat your oven to 400 degrees F.
In a small saucepan over medium heat, melt butter. Add remaining herb butter ingredients and stir to combine. Reduce heat to low while preparing fish.
Place filets in a baking dish sprayed with cooking spray.
Pour herb butter over fish filets. Sprinkle with desired amounts of Old Bay Seasoning and pepper. Top with sliced green onions.
Bake (uncovered) for 10-15 minutes, or until fish are fully cooked and flaky.