the fastes way? Go to the US and find a part 61 school (plenty). Find an instructor who is willing to fly with you almost exclusivly every day (plenty). Bring rougly 3000USD with you for flight lessons. Your all set.
According to Rod Machado, there was a instructor once who finished a student off in under 2 weeks. Of course, you would have to be very competent to pull that off too.
Ground Classes are not necessary. Just buy a book & study it real good. The knowledge test can be taken whenever you feel like it. It must be before your Solo though.