It's called pide and it looks delicious! Instagram member stark_eats describes how he discovered it at a restaurant in Istanbul:
A bearded gent from northern Turkey, crammed in with his family at the table next to ours, upon noticing our non-Turkish tongues, asked us with guarded suspicion how we found out about this family-run spot. Once we gave him a satisfactory answer, he told us we had chosen wisely, for this was his favorite pidecisi in Istanbul. When we were about to dig in, he told us to first slide the butter around the crust and then eat. Glad we did
-via Thrillist