Miranda Cosgrove -- I'M A KAEPER-HOLIC ... 49ers QB Is Hottest In NFL

Another "iCarly" star has a thing for a HUGE celebrity athlete -- this time, it's Miranda Cosgrove who tells TMZ Sports she thinks Colin Kaepernick is the hottest QB in the NFL.

The 21-year-old actress -- who plays Carly on the Nickelodeon show -- was rockin' her 49ers shirt through LAX yesterday when she told us Kap's not only attractive ... but he's "doing amazing" this season.

They've got a lot in common -- starting with the fact they're both super rich ... because Miranda (who also starred in "School of Rock" back in the day) was listed as the highest paid child actress in 2012. And Colin just signed a $126 million contract.

Of course, Miranda isn't the first "iCarly" star to show interest in a pro athlete -- last year, Jennette McCurdy dated NBA star Andre Drummond for a short time ... but that fizzled pretty quickly.