For 4 people I bought one bag of fresh mussels and cleaned them . . . I like doing it myself better than having the machine do it . . . or you can buy a bag of frozen mussels in their shell.
To clean the mussels you need to rip out the “rope” that sticks out of the shell with a certain energy. You must throw away all the mussels which are open or have a broken shell . . . better safe than sorry! Once all the rope is removed you need to scrub the shells with a metal brush to remove all the dirt.
I poured a couple of tablespoons of olive oil in a large pan and added one or two cloves of garlic then as it was all heating I put all the mussels in the pan. I stirred just enough to have all the mussels be “touched” by the oil and then covered them. I let them cook on low flame stirring once until all the shells were opend.
When the mussels open it means they are cooked. If the mussel did not open it’s shell, it is not good and you MUST throw it away – don’t try to open it !
Once the mussels were cooked, I prepared a large baking sheet and set each of the half shells with mussel on it – discarding the empty half shell – and set it aside.
I filtered the liquid that was left in the pan and set it aside.
I then made some coarse breadcrumbs with some tuscan bread, and mixed it with chopped parsley, chopped garlic and grated parmesan. I then added some of the cooking liquid from the mussels to soften the mixture up – but not enough to make it soggy. You can use panko instead of bread crumbs, but you want to crush it a little bit as it would be too coarse.
With a teaspoon I “filled” the mussel shells in the baking sheet with the bread mixture, then drizzled some olive oil on top and cooked it for 10 – 15 minutes in a hot oven (350F or 180C)