Bring a large pot of salted water to a boil. Add 2 cups of elbow macaroni and cook according to package instructions until just al dente (about 7-8 minutes). Drain and set aside.
In a large skillet, heat 2 tablespoons olive oil over medium heat. Add finely chopped onion and cook until soft and translucent, about 4 minutes. Stir in minced garlic and cook another 30 seconds until fragrant. Add 1 cup chopped cooked turkey bacon and cook for 2 minutes.
Sprinkle 1/4 cup all-purpose flour over the onion, garlic, and turkey bacon mixture. Stir continuously for about 1 minute. Gradually whisk in 2 cups milk, whisking constantly to avoid lumps. Simmer and cook until thickened, about 5 minutes.
Reduce heat to low. Stir in 2 cups shredded smoked Gouda and 1 cup shredded cheddar cheese until melted and smooth. Season with 1 teaspoon mustard powder, 1/2 teaspoon black pepper, 1/2 teaspoon paprika, and 1/2 teaspoon salt. Adjust seasoning as needed.
Add cooked elbow macaroni to the cheese sauce and stir until evenly coated.
In a small bowl, combine 1/2 cup breadcrumbs with 2 tablespoons melted butter. Mix well to coat evenly.
Transfer macaroni mixture into a greased 9x9 inch baking dish. Sprinkle breadcrumb mixture evenly over the top. Bake at 350°F (175°C) for 25-30 minutes until topping is golden and casserole is bubbly.
Remove from oven and let rest for 5 minutes before serving.