In a large bowl, whisk eggs, milk, creme fraiche, salt and pepper. Stir in cubed brioche, tarragon, lemon zest and lemon juice. Transfer half to a buttered 3-qt. baking dish; top with lobster meat, then remaining bread mixture. Cover; refrigerate overnight. Bake at 350 degrees until just set, about 1 hour. Top with burrata and chopped tarragon.