Preheat oven to 375°F (190°C).
In a small bowl, toss apple slices with caramel sauce and warmed peanut butter until evenly coated.
Transfer the apple mixture into a small individual-sized ramekin or oven-safe dish.
In a separate bowl, combine oats, flour, brown sugar, cinnamon, and salt.
Cut the cold butter into the dry mixture using a fork until it reaches a crumbly texture.
Spread the crumble topping evenly over the apple mixture.
Bake for 20 minutes or until the topping is golden brown and the apples are tender.
Allow to cool for 5 minutes before serving.