1Make hollandaise sauce as directed on package, adding lemon juice and tarragon. Cover to keep warm. In medium bowl, stir Bisquick mix, buttermilk, cheese, oil and 1 of the eggs with fork or whisk until blended. Let stand 5 minutes.
2Heat waffle maker; brush with additional oil. Pour batter onto center of hot waffle maker, following manufacturer’s directions for recommended amount. Close lid; bake 5 minutes or until steaming stops and waffles are golden brown.
3Meanwhile, in 3-quart saucepan, heat 2 to 3 inches water to boiling; reduce to simmering. Add vinegar. Break remaining 4 eggs, one at a time, into custard cup. Holding cup close to water’s surface, carefully slip eggs into water. Cook 3 to 5 minutes or until whites and yolks are firm, not runny. Remove with slotted spoon.
4Stack 2 waffles; top with 2 slices prosciutto, 1 poached egg and desired amount of hollandaise sauce. Garnish with chives.