Place the cleaned fish in a flat baking dish and drizzle with the lemon juice, salt and pepper.
Cut the spring onions into rings and sauté in the melted butter for 2 minutes. Peel the garlic clove and press it with the onions, season with salt and pepper.
Pour the onion vegetables over the fish fillets. Spread the grated cheese on top. To make the cheese nice and crispy, I sprinkle 1 tablespoon of breadcrumbs over it. Bake the fish in the oven at 200 degrees for about 20-30 minutes (depending on the thickness of the fish pieces).