If the goal is to make as few countries as possible, France was undergoing some dynastic trouble in the 1500s. If Portugal had won the Castillan Succession War, you would have an Eastern Iberia allied to France and a weaker Aragon to be shared between those kingdoms. Poof! One less kingdom. You can merge France and Iberia later using a Royal Mariage, for example with François Ier.
In the North, if England had attacked Scandinavia with French support, there's a way to reduce the amount of countries too.
However, in the Balkans it would mean expanding Austria, Russia, Greece or ottomans.
In my view, you can make this : Franco-Iberia in the West, frontier on the Rhine in the north, Piemont-Sardinia added in the South; Anglo-Scandia as the Septentrion Kingdom (Denmark, UK, Sweden, Norway); Russia; Germany is born from Bavaria instead and has added Bohemia to its lands; Austria stayed united (no problem in second Monarchy of Hungary or Transleithania), with Romania annexed; a New Byzantium in the south covers Greece, Thracia, Bulgaria and Albania; Serbia, Bosnia and Illyria taken over by Italian kingdom (from ashes of Aragonese Sicily as France crushed Savoy)