Preheat oven to 350 degrees F. Lightly grease a muffin tin with non-stick spray, set aside.
Bring a large pot of water to a boil and cook the macaroni until al dente, so they are still a little firm (about 8 minutes). Drain and place in a large bowl.
Add the butter and egg to the bowl and stir to combine. Stir in the milk and 1/2 cup of the pizza sauce. Add the garlic, Italian seasoning, colby jack cheese, 1 1/2 cups of the mozzarella cheese and pepperoni slices and stir to combine.
Scoop the macaroni noodles into the prepared muffin cups, so they are piled high (I got about two ice cream scoops into each one).
Use the remaining pizza sauce to spread on top of each muffin cup, followed by the remaining mozzarella cheese. Combine the bread crumbs, melted butter and salt in a small bowl and whisk to combine. Sprinkle the tops with the crumb mixture.
Bake for 25 to 30 minutes to until the tops are golden brown. Let cool slightly before running a knife around the edges of the muffins to remove from tin. Enjoy!