1Heat oven to 400°F. Grease or spray cookie sheet. In medium bowl, stir together Bisquick mix and boiling water; beat vigorously 20 strokes. On work surface generously sprinkled with Bisquick mix, gently roll dough to coat. Shape into a ball; knead 10 times.
2Roll out dough 1/8 inch. Cut with 2-inch round cutter dipped in Bisquick mix. Place about 2 inches apart on cookie sheet. In small bowl, mix mayonnaise, Parmesan cheese and onion; mix well. Spread each round with 1/2 teaspoon mayonnaise mixture. Top with slightly less than 1 teaspoon artichokes and another 1/2 teaspoon mayonnaise mixture. Place 1 slice tomato on each round, and top with 1 teaspoon mayonnaise mixture.
3Bake 10 to 12 minutes or until golden brown and puffy. Garnish with parsley. Serve warm or at room temperature.