2 tablespoons unsalted butter
1 medium Walla Walla onion, cut in half, then into very thin slices
2 pounds mussels, cleaned
3 slices cooked, good-quality bacon, drained and broken into 1-inch pieces
1 cup hard cider
1/2 cup creme fraiche
Freshly ground black pepper
1/2 bunch flat-leaf parsley, chopped, for serving
Melt the butter in a large saucepan or Dutch oven over medium-high heat. Add the onion and cook for 6 to 8 minutes, stirring often, until translucent.
Rinse and drain the mussels; discard any whose shells are broken or damaged.
Add the bacon and mussels; stir to coat with the butter, then add the cider and creme fraiche and stir to coat. Cover and cook for about 4 minutes, until the mussels have opened. Discard any that have not opened.
Season with salt and pepper to taste, then add the parsley and stir to combine. Divide among individual wide, shallow bowls. Serve hot.