Begin by crushing the Oreo cookies in a food processor until they form fine crumbs. If you don't have a food processor, you can place the cookies in a zip-top bag and crush them with a rolling pin.
In a mixing bowl, combine the crushed Oreo cookies, softened cream cheese, and Nutella. Mix until well blended and smooth, guaranteeing there are no visible lumps.
Roll the mixture into 1-inch balls and place them on a parchment-lined baking sheet. Once all the mixture is rolled, refrigerate the truffles for about 30 minutes to firm up and maintain their shape.
While the truffles are chilling, melt the chocolate almond bark in a microwave-safe bowl in 30-second intervals, stirring in between, until smooth and fully melted.
Remove the truffles from the refrigerator. Dip each truffle into the melted chocolate, guaranteeing they are evenly coated. Allow excess chocolate to drip off and then place them back on the lined baking sheet.
If desired, sprinkle optional toppings onto the truffles before the chocolate sets. Refrigerate again for about 15 minutes to allow the chocolate coating to harden.