In the bowl of a stand mixer with the paddle attachment cream together the butter, cream cheese, and shortening for about 3 minutes. Add the powdered sugar, 1 cup at a time, incorporating fully before adding the next cup. Add the apple flavoring mix in.
For the caramel, if you are using caramel candy, unwrap 8-10 caramels and place in a microwave-safe bowl. Microwave for 30 seconds and remove to stir. If it's needed, microwave for 20 more seconds until all of the caramel is melted together (careful, the bowl is hot!!). Make sure the heavy cream is room temp (or zap in the microwave for 15-20 seconds) and stir it into the caramel. You need the caramel to be pourable. If you are using caramel sauce from the jar, warm up in the microwave for about 20 seconds before adding the heavy cream and drizzling in.
With the mixer on low, drizzle the hot caramel into the frosting as quickly as you can. The caramel needs to be warm so it will melt into the frosting.
Once everything is incorporated, remove the bowl from the mixer and place the frosting in the fridge until you are ready to use it.
Frost right before serving or store frosted treats in the fridge until you are ready to serve them.