Baking – The chocolate chips in the chocolate chip cookies dont rise to the top

Chocolate is in is most essential form made up of cocoa butter and cocoa solids. The chocolate you buy is tempered, the crystals in the cocoa butter are aligned and properly formed, this is what keeps it shiny and gives it a snap.

When the chocolate melts, without tempering, in the cookie the crystals in the cocoa butter melt but do not form properly again, this means the chocolate becomes soft, dull and 'blooms' fat which is where the cocoa butter rises to the surfaces forming a white layer (this will disappear upon melting).

Also in a cookie there will be a high proportion of fat and when the chocolate melts it combines with the fats (in the butter) and will create essentially pockets of chocolate glaze, which obviously doesn't set hard.

Your dough warmed up and the fat started to melt. In between batches, keep the dough cold in the fridge.

Over-mixing the dough will also contribute to cake like cookies if a whole batch comes out like that.