Add 6 tablespoons olive oil to a saucepan; drop in the crushed garlic, and set over medium heat; when the garlic is fragrant and sizzling, stir in the onion slices, bay leaves, salt, and pepper flakes.
Cook for a couple of minutes, tossing and stirring, just until the onions begin to wilt but still have some crunch.
Pour in the wine, and bring to a boil; immediately dump all the mussels into the pan, tumble them over quickly; cover tightly, and turn the heat up to high.
Steam the mussels for 3 minutes, frequently shaking the covered pan, then toss them over, with a wire spider or wide slotted spoon.
If the mussel shells have already opened (or almost all are open), leave the pan uncovered--otherwise, replace the cover and steam a bit longer.
As soon as the mussels have steamed open, sprinkle 1/4 cup bread crumbs all over the pan; quickly tumble the mussels over and over, still on high heat, so their liquor and the crumbs fall into the bubbling pan juices and create a sauce( if the pan sauce is still thin after a minute of bubbling, sprinkle in more bread crumbs).
Finally, drizzle 2 more tablespoons oil and sprinkle the chopped parsley on top, and toss briefly to distribute the seasonings.
Turn off the heat, set the pan in the center of the table, and let people scoop mussels and sauce into their own warm soup bowls (and remember to put out extra bowls for the shells).
Serve with good crusty bread for mopping up the sauce.