1. Adjust oven rack to lowest position and heat oven to 500° F. Heat oil, garlic, and pepper flakes in large roasting pan over medium heat; cook, stirring constantly, until fragrant, about 30 seconds. Add wine, thyme sprigs, and bay leaves and bring to boil. Cook until wine is slightly reduced, about 1 minute. Add mussels and salt. Cover pan tightly with aluminum foil and transfer to oven. Cook until most mussels have opened (a few may remain closed), 15 to 18 minutes.
2. Remove pan from oven. Push mussels to sides of pan. Add butter to center and whisk until melted. Discard thyme sprigs and bay leaves, sprinkle parsley over mussels, and toss to combine. Serve immediately.
OVEN-STEAMED MUSSELS WITH HARD CIDER AND BACON
TO MAKE: Omit garlic and red pepper flakes. Heat oil and 4 slices thick-cut bacon, cut into 1/2-inch pieces, in roasting pan until bacon has rendered and is starting to crisp, about 5 minutes. Proceed with recipe as directed, substituting dry hard cider for wine and 1/4 cup heavy cream for butter.
OVEN-STEAMED MUSSELS WITH LEEKS AND PERNOD
TO MAKE: Omit red pepper flakes and increase oil to 3 tablespoons. Heat oil; 1 pound leeks, white and light green parts only, halved lengthwise, sliced thin, and washed thoroughly; and garlic in roasting pan until leeks are wilted, about 3 minutes. Proceed with recipe as directed, omitting thyme sprigs and substituting 1/2 cup Pernod and 1/4 cup water for wine, 1/4 cup crème fraîche for butter, and chives for parsley.
Chef's Notes:
Discard any mussel with an unpleasant odor or with a cracked or broken shell or a shell that won’t close. Serve with crusty bread.