One of my favorite first courses is mussels in garlic butter. It's very easy to make. You can buy fresh mussels at the market. I have also used canned mussels but they are harder to find. When I used to visit my husband's family in Philly, I would load up on the imported canned mussels by the case but now fresh are readily available in our area all year long.
The only work to serving mussels is cleaning them. Many fishmongers will sell them already cleaned but if you are going to clean them yourself, remove the "beards" (the little fuzzy furries outside the shell) with a stiff brush. Make sure you discard any mussels that are open. They should all be tightly closed before cooking. Rinse well and repeat so you make sure you get rid of any sand or beard bits clinging to the shells. The shells should be smooth and clean and tightly closed.
If you are cooking a lot of mussels, say a couple of pounds or more, I find it easier to steam them in a little chicken broth with wine, then drain before adding the herbed garlic butter and broiling. If cooking just a pound or so, you can skip pre-cooking them. Just place them in a casserole or oven-proof pan with a lid.
Spread the uncooked, clean mussels out in the dish or pan. Cover the pan or casserole with a tight fitting lid and bake in a pre-heated oven at 400 degrees for about 10 minutes until the mussels start to pop open. If you don't have a lid to fit, you can use aluminum foil. Do not overcook.
While the mussels are baking, melt about a 1/4 pound of sweet cream butter per pound of mussels and stir in some finely diced cloves of fresh garlic. You can also add a splash of white wine and a little freshly chopped parsley. Remember to save at least half of your fresh parsley to chop and add when serving since bright green parsley is always appealing on the plate. When the mussels have cooked 10 minutes, add the melted butter, garlic and parsley mixture. I like a lot of garlic - at least a couple or three minced cloves per serving. Continue baking for another 5 to 10 minutes until you smell the garlic. If any mussels did not open, discard them.
I like to serve mussels in garlic butter over toasted French or Cuban bread. I pan fry slices of crusty bread in a little butter and olive oil and place it in the bottom of a rim soup bowl or deep plate. Then, I place the cooked mussels on the bread. The final step is to pour the garlic butter mixture on the mussels and sprinkle with some fresh parsley. Some mussels may come lose from the shell but it doesn't matter. It makes a beautiful presentation just piled onto the bread and it smells wonderful! Of course, you will eat the bread in the bottom of the bowl since it is full of garlic butter sauce but you might also want some crusty bread to dip into any leftover sauce.
When mussels are inexpensive, W4D and I often eat this dish as an entree. When we crave them and mussels are pricey, we have them as a first course. I also love mussels in marinara sauce or as part of seafood pasta dishes or on the shell with an herbed cream sauce but I'll save those recipes for another time.
BTW, I like to take pictures of the foods I cook. You are welcome to link to my photos but please give proper credit to the photographer. That would be me.