Next in a large mixing bowl or stand mixer, add in flour, sugar, salt, and baking powder and combine. Then, continue with the oil, egg, and milk and mix well. Lastly fold in the apples.
Once done, fill cupcake liners that have been sprayed with non-stick cooking spray, up to the top.
Next, combine all of the crumb ingredients in a bowl and mix them together with a fork.
Sprinkle the crumb ingredients evenly over each muffin.
Bake 25-30 minutes or until the crumb topping has browned.
Drizzle with caramel if you would like.
Notes
This made 10 regular sized muffins for us; however, original source says 8. It will vary based on size.