Preheat oven to 350 degrees. Spray mini-muffin tins with nonstick cooking spray.
In a small bowl, combine bread crumbs, olive oil and salt; set aside.
Bring a large pot of lightly salted water to a boil. Add the macaroni and cook for about 8 minutes, to al dente. Remove from the heat, drain and return macaroni to pan; stir in the butter and egg until pasta is evenly coated. Stir 1 cup of Cheddar cheese, milk and all of the mozzarella cheese into the pasta. Spoon into the prepared muffin tins. Sprinkle the remaining Cheddar cheese and the bread crumb mixture over the tops.
Bake for 30 minutes until the topping is golden and "muffins" are slightly firm to the touch. Allow to cool for a few minutes before removing from the pan. This allows the cheese to set and the "muffins" will hold their shape.