Preheat your oven to 350°F (175°C).
In a mixing bowl, mix together the sourdough discard and chopped apples.
Add the butter to the mixture and stir until everything is well combined.
In a separate bowl, prepare the cinnamon streusel topping.
Spoon the muffin batter into a muffin tin and generously sprinkle the streusel on top.
Bake in the preheated oven for about 20 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool slightly before drizzling them with caramel.
