Dice the onion and the bacon, leaving 1/2 of 1 strip whole.
Clean and debeard the mussels by tugging sharply toward the back of the shell. Discard any mussels that don't close when submerged in water or when lightly tapped. Drain off tap water and cover with a damp towel until ready to cook.
Crisp bacon in a large, wide sauté pan, about 8 minutes. When crisp, remove all but the 1/2 piece from the pan.
Add the onions and cook until softened, 2-3 minutes.
Add in the cider with the fresh thyme and bring to a rapid simmer. Cook until reduced by 1/2, about 8-10 minutes.
Add mussels to the pan and cover immediately. Cook for 4 minutes.
Remove the lid and discard any mussels that did not open. Pour in cream and allow to simmer 1-2 minutes.
Taste the broth and add pepper, or salt if needed.
Serve with the crisp bacon sprinkled over top and bread for dipping if desired.
Notes
*you can also use 1 large shallot, or white onion*If you want non-alcoholic, choose apple cider, preferably not too sweet.