1. Melt butter in small saucepan over medium-low heat. Stir in garlic and shallot; cook 3 to 4 min., until garlic is soft. Stir in herbs; cook 2 min. Open champagne; pour 1/2 c. champagne into butter; stopper champagne. Bring sauce mixture to simmer; cook an additional 3 to 5 min. until sauce is reduced slightly. Add sea salt to taste. Keep sauce warm.
2. Rinse frozen Alaska Crab legs under cold running water to remove any ice glaze; pat dry with paper towels. Discard towels. Steam or boil crab in large pot, 8 to 10 min. for frozen crab or 3 to 4 min. for fresh/thawed crab, until heated-through.
3. Serve crab with dipping sauce, warm bread and chilled champagne.