For the topping, combine all ingredients in a small bowl and set aside.

Preheat oven to 400°F and butter 4 individual ramekins or a 1-quart baking dish.

Melt the 1 tablespoon butter in a large skillet over medium-high heat. When it begins to bubble, add the onion, peppers, celery, artichokes, and garlic and sauté for about 3 minutes, stirring. When the vegetables have wilted and are just barely beginning to color, sprinkle in the flour and stir. Cook 2 minutes more, then whisk in the sherry and milk. Bring to a boil, whisking as it thickens. If the mixture becomes too thick (if it seizes up and  pulls away from the aide), add a little more milk to loosen.

After about 2 minutes, add the cream and bring the mixture back to a boil, whisking the entire time. Lower the heat and simmmer for about 5 minutes more, until the mixture is smooth and any raw flour taste is gone. Season to taste with asalt, eppper, and hot saucde, then stir in the mustard, tarragon, lemon juice, and lemon zest. Remove from heat a dn set aside.

Heat the olive oil in a medium sauté pan over medium-high heat and sauté the mushrooms until golden brown. Add the mushrooms to the cream sauce. Put the crabmeat in the mushroom sauté pan and heat until it is warmed through and the liquid has evaporated, about 2 minutes. Take one last look for shells at this point. Add scallions to the crabmeat mixture and stir, then remove from heat. Fold the crabmeat into the cream sauce. Taste and adjust seasonings—it may need more lemon juice.

Divide the mixture evenly among ramekins or pour into the baking dish. Sprinkle with the topping and bake for 6-8 minutes, until browned and bubbly. Serve immediately.