Place Oreos and Nutella in a food processor. Process until a smooth mixture remains and a ball starts to form while the processor is running. This will take at least a minute, depending on your food processor.
If truffle mixture is too soft to roll, chill for 15 minutes. Otherwise, scoop 1 tablespoon balls of truffle dough onto a wax paper lined cookie sheet. Chill at least one hour. (I do not recommend chilling the mixture that long until after you’ve scooped the truffles. It becomes hard and hard to scoop, so if you need to chill the dough first, just do it about 15 minutes, then scoop, then chill again.)
Melt chocolate according to package directions. I like to use melting chocolate like Candiquik and almond bark because it’s easier to melt and won’t seize like chocolate chips often does. You can find this chocolate in the regular baking aisle. My chocolate melted in about 1-1/2 minutes on high power, and I stirred it every 30 seconds.
Dip each truffle in the chocolate, tap off excess, and place back on cookie sheet. Sprinkle with sprinkles, if desired. Chill to set. Store in refrigerator for up to 5 days.