Charbroil them on the grill. Since you have the shells, this is a great way to cook them if you own a grill, either gas or charcoal will work fine, it's just faster on the gas grill since there is not much wait time for it to get hot.
Put the oysters in the shells and place them on trays in the fridge while making the ingredients to charbroil them.
For that amount of oysters you'll need the equivalent of 1 lg. bag of spinach. I use Swiss Chard out of my garden if I don't have spinach.
1 small onion diced
3 cloves garlic minced
Spinach or Swiss Chard
1 stick real butter
2 oz. Parmesan Cheese
2 oz. Italian Bread Crumbs
Melt the butter in a saucepan, add 2 cloves of the garlic and let this cook slowly to infuse the garlic flavor in the butter. In the meantime, put the onion in about 1 tsp. oil in a pan and let it start to wilt. Next add the remaining garlic and greens and let them wilt down for about 15 minutes. They will release a good bit of water as they cook down. When they are done, drain the greens well. I like to put them in a sieve and press them to get as much liquid out as I can. In a small dish, mix the cheese and bread crumbs till blended. Now you're ready for grilling.
Place the oysters on the grill directly over the heat and let them start cooking in their shells. Just as they start bubbling on the outer edges, place a small portion of the cheese, breadcrumb mixture on each of them. Follow this by placing the wilted greens and then brush each oyster with the garlic/butter mix and let them cook till the oyster curls up a bit, but not so long as to dry them out. Just before removing them, hit them with another light brushing of the butter/garlic mix and eat while hot.