Ex-NFL Cheerleader -- Guilty of Raping 15-Year-Old Boy

An ex-NFL cheerleader has just pled guilty to raping a 15-year-old boy she spotted on Instagram ... and now could face up to 15 years in prison.

As we previously reported, 48-year-old Molly Shattuck -- who cheered for the Baltimore Ravens in '05 -- was indicted back in November for 2 counts of 3rd degree rape for incidents that took place in September '14.

Officials say Shattuck began seducing the boy back in May after she saw his picture on Instagram -- and first got physical with him in the back seat of her car in a middle school parking lot ... with kissing and touching.

But investigators say things escalated during Labor Day weekend ... when Molly seduced the boy at a rented beach house she was staying at with her own kids -- performing oral sex on him at least 2 times.

Now, we've learned Shattuck struck a plea deal with prosecutors in which she agreed to plead guilty to one count of rape in the 4th degree ... and could face up to 15 years in prison when sentenced in August.