15 miles probably puts you out around 60 minutes, depending on how intense a ride you're doing (70-75%/max HR) you might not need to eat anything.
If you do I would suggest fruit not dairy pre ride.
Maybe nibble on some gummy bears or fig bars during your ride if it's intense enough.
Carb loading needs to take place a minimum of 12 hours pre ride.
Post ride fueling is as important. Yogurt, bagel.
I stopped eating before rides under 90 minutes. I bring a Harvest Bar, fig bar and some gummy bears and keep nibbling on them about every 15 minutes.
My rides are getting up to around 30 miles at 75-80%/max.
After ride, usually a bagel or a yogurt, depending on intensity, within 30 minutes and in a couple of hours a good feeding.
And stay hydrated. I bring 2 water bottles, one 50/50 water/gatorade and one 70/30 water/gatorade.
The most important thing is watch out for lunatic drivers, usually men in their 30-45s driving trucks.