In a food processor or blender, process the Oreos until they are crumbs. If you do not have a food processor, put the Oreos in a big ziplock bag and hit them with the back of a wooden spoon or roll them out using a rolling pin. In a small bowl, mix together the Oreo crumbs and melted butter. Press this mixture into the bottom of your pan and place in the freezer for 20-30 minutes.
Peanut Butter Filling
In a large bowl, whip the heavy cream on medium speed until stiff peaks form. Add the peanut butter, cream cheese, powdered sugar and vanilla extract and beat for 3-4 minutes on medium-high speed until smooth and creamy. Pour the peanut butter filling onto the Oreo crust and use a rubber spatula to make a smooth & even layer. Place back in the refrigerator for 30-40 minutes.
Chocolate Topping
To make the chocolate topping, combine the chocolate and oil and melt over the stovetop or in the microwave in 15-second increments. Pour the chocolate over the peanut butter filling and tilt the pan so the chocolate spreads over the entire thing. Place desired toppings in the center of the tart. Place back in the refrigerator for 1-2 hours or until the chocolate has set. Store in an airtight container in the refrigerator for 3-4 days.