Hold tomatoes at room temperature until fully ripe. Preheat oven to 350 degrees.Cut a thin slice from the stem end of each tomato.Scoop out pulp (use in stews,soups,etc.).Sprinkle inside of tomato shells lightly with salt;invert on board to drain,about 10 minutes.Combine onion powder,tarragon,1/8 teaspoon salt and black pepper;blend well.Sprinkle each shell with about 1/2 teaspoon seasoning mixture.Break one egg into each tomato.Place on buttered baking pan.Bake until eggs are firm,25 to 30 minutes.Combine bread crumbs,cheese and parsley. Sprinkle around outer edge of each tomato,Dot with butter. Place under a preheated hot broiler until crumbs are lightly browned,1 to 2 minutes.Serves 6.