You just need mussels, tomato based pasta sauce and mozzeralla cheese.
-Steam the mussels for 3 minutes first.
If you don't partially cook it first to remove the liquid, when you bake it later, it will be very wet.
-After steaming the mussels, drain them. You can retain the liquid as seafood stock.
-Spoon pasta sauce to cover fill the shell.
-Top with shredded mozzeralla cheese.
-Sprinkle some chopped pasley if you like.
-Now bake at 180C for 10 minutes or till you see the sauce bubbling out or the cheese and that the cheese has melted.
-Served it hot. It won't be nice once it's cold. Oh, do try with carbonara sauce too. Though, I strongly recommend tomato sauce. I don't know about you. I always feel that seafood (pasta) taste better in tomato based sauce. ;)