Keep mussels in fridge cold for no more than 2 days. Place in sink in colander and debeard, pulling beards toward the hinge, and scrub with potato or kitchen brush under cold water; add to strainer as you work. Discard any mussels that are open if they do not close when knocked together or if the mussel shell has cracked or is broken.
Place rack at center oven and preheat broiler.
Halve bread horizontally. Line a baking sheet with foil and arrange bread cut-side up on it.
Heat a large, deep pan with tight-fitting lid over medium heat with EVOO, 2 turns of the pan. Add butter and melt into oil. When butter foams, add shallots, garlic, lemon zest and pinch red pepper flakes and stir 1 to 2 minutes. Add wine and mussels, turn heat up to high, cover pan and cook 6 minutes, shaking occasionally. Remove from heat and leave covered.
Heat EVOO, butter and crushed garlic in small pot and add a pastry brush.
Broil bread to lightly toast, then brush with warm oil-butter mixture. Sprinkle with cheese, pinch red pepper flakes, some parsley and salt. Broil again until golden, about 3 minutes. Cut bread into 3- to 4-inch pieces.
Uncover mussels, add juice of 1 large lemon, remaining parsley, basil and red pepper flakes and shake or toss. Set bread into pan sauce and juices all around the perimeter of the pan. Serve from pan in shallow bowls with smaller bowl/s set to collect the shells.