Mix the base: In a mixing bowl, combine 36 crushed Oreo cookies and 1 package (8 oz) softened cream cheese. Use a spatula or your hands to mix well until the mixture is evenly combined.
Add the peanut butter chips: Fold in 1/2 cup of Reese's Peanut Butter Chips into the Oreo-cream cheese mixture, ensuring they are distributed evenly throughout.
Shape into balls: Using your hands, scoop out portions of the mixture and roll them into 1-inch balls. Place the formed balls onto a wax-lined baking sheet. Freeze for approximately 15 minutes to firm them up.
Melt the chocolate: In a microwave-safe bowl, melt 2 cups semi-sweet chocolate chips and 1 tablespoon vegetable shortening in 30-second intervals, stirring in between until the mixture is completely smooth and glossy.
Dip the truffles: Once the truffles have chilled, take them out of the freezer. Dip each ball into the melted chocolate, ensuring they are fully coated. Allow any excess chocolate to drip off before placing them back on the baking sheet.
Add the garnish: Immediately sprinkle the tops of the chocolate-coated truffles with 1/4 cup crushed Reese's Peanut Butter Cups before the chocolate sets.
Chill the truffles: Refrigerate the truffles for about 1 hour until they are firm. Once set, they are ready to enjoy!