How to eat 2500 calories at least moderately healthily?

hello, my coach says he wants me to start eating 2300 calories a day, and im finding it very hard to meet this coming up from only 1800 a day, i am planning on eating breakfast, lunch, and dinner, with two snacks. each meal will not go over 600 calories that is the one thing i wont budge on, so that leaves my morning and afternoon snacks to make up 500 cals, i am already up to my head on fruits and veggies, so how do i make that up without eating like pop-tarts or candy bars? thanks in advance