In a mixing bowl, combine mayonnaise, lemon juice, Dijon mustard, and chopped herbs.
Add chopped lobster meat, diced celery, and minced shallot, then gently fold to coat evenly.
Season with salt, pepper, and optional Old Bay seasoning or smoked paprika.
Chill the lobster salad for 10–15 minutes if possible to enhance flavor.
Slice croissants horizontally without cutting all the way through.
Lightly butter the inside of croissants and toast in a skillet over medium heat for 1–2 minutes until golden.
Allow croissants to cool slightly before filling.
Add lettuce or baby spinach leaves inside the croissants if desired.
Spoon generous amounts of lobster salad into each croissant.
Serve immediately with fresh lemon wedges.