Crust: In a food processor, pulse together graham crackers, Oreo cookies, cocoa powder, and salt. Stir in melted butter. Use the flat bottom of a drinking glass (or measuring cup) to press mixture into the bottom and up the sides of a 9-inch tart pan with removable bottom.
Cheesecake Filling: Use a hand mixer to beat together cream cheese, sour cream, and sugar until smooth. (Alternatively, use a stand mixer fitted with a paddle attachment.) Add egg, salt, vanilla, and heavy cream. Mix until incorporated. Scrape dough sides of bowl to ensure thorough mixing. Fold in chopped Oreo cookies.
Transfer filling into prepared crust. Spread into an even layer. Bake in preheated oven for 30-35 minutes until cheesecake is set. Cool tart on wire rack. Refrigerate for at least two hours, overnight is best.
Topping: Spread whipped cream over cooled cheesecake. Garnish with chopped Oreo cookies.
Notes
Tips on cutting cheesecake:Warm knife under hot water and wipe dry before slicing. Wipe knife before each slice. Alternatively, use stainless steel cheese wire.
Storage and Leftovers:
Cheesecake may be baked ahead of time, up to two days before serving. Do not add whipped cream topping until ready to serve.
Store cheesecake tart in an airtight container or cover with plastic wrap to prevent cheesecake from absorbing unwanted flavors of the fridge.
Once fully assembled, cheesecake will last in the fridge for another 2-3 days. However, the whipped cream topping will separate over time.