Use a food processor and pulse cookies until they form until fine crumbs. I like to reserve 3 or 4 cookies from the package to pulse for garnishing the top of the truffles, this is optional. Pour cookie crumbs into a large bowl.
Add the block of cream cheese into the bowl and add peppermint extract. Use your hands ( I think it's the easiest) or a large spoon or spatula, and mix the cookie crumbs and cream cheese together. This step may take a minute or two so be patient and just stick with it. Cookie crumbs and cream cheese are fully mixed together when cookie crumbs are moist and cream cheese is not visible.
Scoop crumb/cream cheese mixture into little balls, about 1.5 tablespoons in size and place on a plate and chill them in the refrigerator for a minimum of 1 hour. Do not skip chilling them because the truffles need to be firm before they are dipped in chocolate.
When you truffles are ready for dipping, melt the white chocolate chips and candy melts in a heat safe proof bowl in the microwave. Heat them for 30 seconds, stir them and then repeat this process until the chocolate and candy melts are fully melted. At this time you can also pulse your extra cookies for garnish.
Dip Oreo balls into the melted chocolate and use a fork to scoop them out and let the excess chocolate drip off. Place truffles on a plate or baking sheet lined with parchment paper. If you want to decorate your truffles with sprinkles or Oreo crumbs add those while the chocolate is still wet. Return truffles back to the refrigerator to set for another 15-20 minutes. Once they are dry they are ready to serve.