Preheat the oven to 375 degrees F.
Fill a large stockpot 3/4 full with salted water and bring to a boil. Plunge the lobsters headfirst into the boiling water and cook, covered, until firm and almost cooked through, 6 to 7 minutes. Drain and transfer with tongs to a large bowl filled with ice water. Drain well. When the lobsters are cool enough to handle, place flat on their backs. With heavy scissors, cut each lobster down the middle from head to tail, being careful not to cut through the hard shell. Press the lobster open so it will lie flat.
Lift out the pink coral (roe), if any, and green tomalley (liver). Discard stomach sac or "lady" from back of head, black vein running from head to tail, and spongy gray tissue. Remove the meat from the tail and leave the claws intact. Coarsely chop the meat and set aside. Place the shells on a large baking sheet.
In a skillet, melt the 1 tablespoon of butter over medium-high heat. Add the shallots, celery, and bell peppers and cook, stirring, for 2 minutes. Add the garlic and cook, stirring, for 30 seconds. Add the chopped lobster meat and cook, stirring, for 2 minutes. Remove from the heat. In a large bowl, combine the chopped lobster meat, reserved tomalley and roe (if desired), sauteed vegetables, cracker crumbs, parsley, tarragon, lemon juice, Essence, and salt. Stir, and add enough melted butter to make a paste-like consistency. Fill the cavity of each lobster with the mixture and place on a baking sheet.
Bake until the mixture is heated through, about 15 minutes. Increase the heat to broil and broil until golden brown and the cracker crumbs crisp, 2 to 3 minutes. Remove from the oven. Line 4 plates with watercress. Place 1 lobster on each plate and garnish with lemon wedges. Serve immediately.
Yield: 4 servings