Pretty sure 5 moves is the fastest you can beat it, optimised this to what seems to be its maximum. Feel free to prove me wrong!
Edit: Got within 10 gold of beating Foccacia on Move 4. Definitely doable.
You must be very delicate: the first few moves allow for no inaccuracy in your play. First, a hint. Within the first move, the knights should be dead, and the enemy must be unable to construct pikemen. Do this by carefully segmenting and cutting off territory. Continue until you have won, the rest is comparatively trivial. If you need another hint, just ask!