Preheat the oven to 350ºF. Line an 8x8 baking pan with parchment paper.
In a small bowl, combine the crushed Oreos and butter. Press them evenly into the bottom of the lined baking pan. Bake for 8 minutes. Remove from the oven and set aside on a wire rack to cool.
In the bowl of a stand mixer (or you can use a hand mixer), mix the cream cheese until smooth. Add the sugar and vanilla and mix again.
Add one egg and mix just until combined. Scrape the sides of the bowl. Add the other egg and mix again until combined.
Fold in the sour cream.
Spread 1/2 the cream cheese mixture over the cooled Oreo crust. Sprinkle the chopped Butterfingers and Reese's cups evenly over the batter.
Drizzle the caramel topping over the candies, then spread the remaining cream cheese mixture over everything.
Bake at for about 35-40 minutes or until the cheesecake has set and the edges are lightly browned.
Make the ganache:
To prepare the chocolate ganache topping, heat the heavy cream for about 30 seconds in the microwave. Do not allow the heavy cream to boil.**
Place the chocolate chips in a medium-size bowl and pour the heated cream over the chocolate chips. Cover the bowl with a plate or a lid and allow it to sit for 3-4 minutes.
Mix the chocolate chips and the cream together until the cream is completely mixed in with the chocolate. The ganache should be completely smooth.
Spread the ganache over the top of the cooled cheesecake evenly and allow it to set in the refrigerator preferably overnight, but at least for 4 hours.
After the cheesecake has set, remove the bars from the pan by pulling up on the parchment paper. Discard the paper, place the cheesecake on a cutting board and cut it into 16 squares.
Make the peanut butter frosting:
In a small bowl, use a hand mixer to cream together the butter and peanut butter until smooth.
Add the milk and powdered sugar, then beat until creamy. Drop this by tablespoons on top of each square of cheesecake, or use a decorating bag and tip (Wilton tip 1M) to make a simple swirl on each square.
Store in an airtight container in the refrigerator.
**If the heavy cream is too hot, it may burn the chocolate and make the chocolate seize. It should be heated, but not boiling hot.Refer to the article above for more tips and tricks.The calories shown are based on the bars being cut into 16 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information. The information in the nutrition box are calculated through a program and there is room for error. If you need an accurate count, I recommend running the ingredients through your favorite nutrition calculator.**