Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente (usually about 7-8 minutes). Drain well and set aside.
In a medium saucepan, melt the butter over medium heat. Once melted, whisk in the flour to create a smooth roux. Cook for 1-2 minutes, stirring constantly, until the mixture turns a light golden color.
Slowly pour in the milk while whisking continuously to prevent lumps. Stir in garlic powder, onion powder, mustard powder, salt, and pepper. Continue cooking and whisking until the sauce thickens and coats the back of a spoon, about 5-7 minutes.
Remove the sauce from heat and stir in the shredded cheddar and mozzarella cheese until melted and smooth. Taste and adjust seasoning if needed.
In a large bowl, mix the cooked macaroni with the cheese sauce until well coated. If using turkey bacon, fold it in now for an extra savory layer.
Transfer the cheesy pasta mixture into the prepared baking dish. Sprinkle the breadcrumbs evenly over the top to create a crisp crust.
Bake in a preheated oven at 350°F (175°C) for 20-25 minutes or until the top is golden brown and the edges are bubbling.
Remove from the oven and let it rest for a few minutes. Garnish with chopped parsley, if desired, then serve warm.