My mom was not a fish eater, but this is one recipe she would use for fish that everyone liked, even she. There are no ingredient amounts, so you just have to decide how much of each thing you want and go for it. LOL I will give you an idea of how much we used for 4 servings. Sometimes we would also squeeze half a lemon over the fish before adding the toppings.
Preheat oven to 400 degrees and line a rimmed baking sheet or casserole with foil. Spray lightly with cooking spray.
Melt the butter in a medium saute pan and add the chopped or sliced onion. Sweat the onion on medium low until soft and translucent. Increase the heat to medium and add garlic, cook for a minute until fragrant. Add Chopped tarragon and thyme leaves. Continue to cook until mixture starts to take on a little color.
Salt and pepper fillets on both sides and place in foil lined pan, Spread the sauteed topping over the fillets and then top with buttered crumbs.
Bake until fish flakes easily and crumbs are browned, about 10 to 15 minutes, depending on the thickness of the fillets.
Note: When I made this dish, I added some chopped peppers to the veggie mix and sauteed the veggies and baked the dish all in the same oven-safe skillet.