Arrange oven with rack on the highest level. Prep a baking sheet with oil or butter.

In a small bowl, mix butter, mayo, Parmesan, hot sauce, salt and pepper. Set aside.

Pat grouper fillets dry on both sides and arrange on baking sheet.

Squeeze half of the lemon over the fillets, being sure to prevent seeds from falling out. Brush to distribute juice equally.

Turn the oven’s broiler on high and let it warm up a few seconds.

Broil the fillets for about 5 minutes, watching carefully to see that they don’t brown too quickly. When they look opaque and you can flake them with a fork, remove.

Remove tray from the oven. Spread the butter mixture evenly on top of fillets. Sprinkle with breadcrumbs, if using.

Return fillets to broiler for about another 30 seconds. Top will be brown and bubbly, with a crispy finish.

Remove from oven and serve with the rest of the lemon juice squeezed on top. Enjoy!