Are you aiming to do this with fresh fruits? Concentrates - frozen or VH/canned?
If fresh fruit, you'd wanna make the wine per-normal fruit wines... Freeze & thaw the fruit, mash it up & hit it with pectic enzyme while it thaws, adjust total volume based on TA reading, adjust sugar to 1.080 & ferment with 1116 or 1122 yeasts.
If you wanna go the "skeeter pee" route, you could do a basic SP wine, backsweeten with Welches white grape + raspberry frozen concentrate...
Either way, layering in the chocolate is the same procedure - when the wine is cleared & bulk aging, add chocolate (the higher the % of cocoa, the better; less butter/oil.. I just recently found 100% cocoa chocolate) in pieces and allow them to rest in the bottom of the carboy, stir occasionally depending on desired results... Taste often, rack off the chocolate when its where you want it..
Age & bottle it.