Ashley Tisdale -- Stalker Pleads No Contest ... Gets Probation & Head Shrinking

Ashley Tisdale's obsessed fan just pled no contest to felony stalking -- and will serve no further jail time ... though he'll still have to stay the hell away from Ashley for a long time.

Nicholas Fiore was arrested back in June for violating the restraining order she got against him -- after claiming Fiore threatened to shoot her, and bombarded her with more than 18,000 tweets.

The judge gave Fiore credit for jail time served, one year of outpatient counseling, 5 years probation ... and $350 in fines and fees.

A criminal protective order -- requiring Fiore to stay 100 yards away from Tisdale -- will remain in effect for the next 5 years.