Building muscle

Sounds like you want to recomp. Check out this thread. https://community.myfitnesspal.com/en/discussion/10177803/recomposition-maintaining-weight-while-losing-fat/p1

There are no "best foods". You can start by eating at maintenance and keeping your protein around 0.8-1g per lb bodyweight

The best foods to eat for fat loss are ones that keep you in a calorie deficit

The best foods to eat for building muscle are ones that put you in a calorie surplus

These things don't usually happen at the same time...

If you are already relatively lean and at a healthy weight, you could look in to recomp, eating at maintenance whilst following a progressive lifting program to slowly lose fat whilst gaining muscle.