Preheat oven to 375 degrees F (190 degrees C). Grease a 9x13 inch baking dish.
Bring a large pot of lightly salted water to a boil. Cook macaroni in boiling water, stirring occasionally until cooked through but firm to the bite, 8 minutes. Drain.
Melt butter in a large saucepan over medium heat. Stir in flour, salt, pepper, and garlic powder; cook 1 minute. Gradually whisk in milk. Increase heat to medium-high and bring to a boil, stirring frequently. Boil and stir 1 minute. Remove from heat and stir in cheddar, Monterey Jack, and Parmesan cheeses until cheese is melted.
Mix macaroni and cheese sauce together in the prepared baking dish. Sprinkle bacon over the top.
Bake in preheated oven until bubbly and golden brown, about 25 minutes.
Interesting Facts
Macaroni jumble is a classic American comfort food dish.
It is a great dish to serve for family dinners or special occasions.
The dish is also known as mac and cheese jumble or mac jumble.