In a large pot, or dutch oven large enough to accommodate the mussels, begin to cook, and brown the bacon. Once bacon begins to bronze, add in the leeks, salt and pepper, and continue to sweat over medium heat until the leeks begin to become translucent.
Add in the apple cider and cream, allow these liquids to reduce by half. Pour in the beer and reduce again by half.
Add mussels into the pot, cover and allow to cook until the mussels open. Approximately 5-7 minutes.
Serve the mussels immediately. Garnish with fresh herbs or scallions as desired.