Stir together baking mix, next 3 ingredients, and 1 egg in a medium bowl until blended. Let batter stand 5 minutes.
Meanwhile, add water to a depth of 3 inches in a large saucepan. Bring to a boil; reduce heat, and maintain a light simmer. Add vinegar. Break remaining 4 eggs, and slip into water, 1 at a time, as close as possible to surface. Simmer 3 to 5 minutes or to desired degree of doneness. Remove with a slotted spoon. Trim edges, if desired.
Cook batter in a preheated, lightly greased waffle iron according to manufacturer's directions until golden.
Prepare hollandaise sauce according to package directions, adding lemon juice and tarragon.
Stack 2 waffles, and top with 2 prosciutto slices, 1 poached egg, and desired amount of hollandaise sauce. Garnish, if desired.
Note: For testing purposes only, we used Bisquick All-Purpose Baking Mix and Knorr Hollandaise Sauce Mix.