Well, a 3:15 flight will get you a pickup time from DME between 12-12:30. You need to be back at the resort, ready to go, waiting at the DME bus stop 15 mins before the pickup time. So, let's say your pickup time is 12:15. You should be at the bus stop, bags in hand, by noon. This means you need to be back at POP by 11:30ish...to get anything you left with luggage assistence and use the bathrooms.
You need to be out of the CR by 10:45 to get a bus back to POP...walk back to MK takes about 8 mins (monorail takes close to 25!!), then a possible wait for the bus to POP.
Not sure you're going to have enough time. Chef Mickey's is the one spot that seems to take forever for all the characters to make a circuit. And, they seldom seat you ontime...especially that late in the morning.
A seating at 10am is going to take you up to 11ish, maybe a bit later. I would get a cab back to POP at that point. no way will you make it using Disney buses...just cutting it too close.