Line a cupcake pan with liners and set aside. Using a food processor or a rolling pin with a ziploc bag, crush the Oreos into fine crumbs.
Combine the crumbs with melted butter until the mixture resembles wet sand. Spoon about a tablespoon of this mixture into each lined cupcake cavity and press firmly with the bottom of a ¼-cup measuring cup. Set aside.
Filling
In a stand mixer bowl, cream together softened cream cheese and sugar until smooth. Add in the heavy whipping cream and peppermint flavoring, mixing thoroughly until smooth and creamy. Divide the filling evenly among the crusts, smoothing each top.
Refrigerate the cheesecakes for at least 2-4 hours until set.
Combine chocolate chips, 2 tablespoons heavy cream, and peppermint flavoring in a microwavable bowl. Heat in 30-second intervals, stirring until smooth. Set aside to cool slightly.
In a stand mixer, whip the remaining heavy cream with powdered sugar on medium-high speed until stiff peaks form. Transfer to a piping bag with a star tip.
Assemble and Decorate
Once set, top each cheesecake with a spoonful of the peppermint chocolate ganache, spreading it evenly just inside the edges. Pipe a dollop of whipped cream on each, then sprinkle with crushed peppermint pieces.