Butlers, the Irish chocolate-and-coffee chain, has its Islamabad outpost in Kohsar Market in F-6 and serves what is probably the best hot chocolate in the city. The cafe spills onto a pavement terrace and is one of the standard meet-up spots for the diplomatic and NGO crowd that lives nearby.
The food menu runs to sandwiches, salads and a long dessert list. Prices are mid-range. A useful daytime stop while exploring the F-6 embassies and shops.