Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
Step 2: Cook the elbow macaroni according to package directions until al dente. Drain well and set aside.
Step 3: In a large skillet or Dutch oven, cook the chopped bacon over medium heat until crispy. Use a slotted spoon to remove bacon bits to a paper towel-lined plate. Reserve 1-2 tablespoons of bacon fat in the skillet.
Step 4: Add the ground beef to the skillet with reserved bacon fat. Cook over medium-high heat, breaking it up, until browned. Drain any excess fat. Add the diced yellow onion and cook until softened, about 5-7 minutes. Stir in minced garlic, salt, and black pepper, cooking for 1 minute until fragrant.
Step 5: Sprinkle the all-purpose flour over the beef and onion mixture. Stir constantly for 1 minute.
Step 6: Gradually whisk in the whole milk and chicken broth until smooth. Stir in the Dijon mustard and smoked paprika. Bring to a gentle simmer, then reduce heat to low.
Step 7: Remove the skillet from heat. Stir in 3 cups of the shredded sharp cheddar cheese and 1 cup of the shredded Monterey Jack cheese until completely melted and the sauce is smooth. Fold in the cooked macaroni, ketchup, and yellow mustard until combined.
Step 8: Transfer half of the macaroni mixture to the prepared baking dish. Sprinkle generously with 1 cup of the remaining shredded sharp cheddar cheese and 1 cup of the remaining shredded Monterey Jack cheese, and half of the crumbled crispy bacon. Top with the remaining macaroni mixture.
Step 9: Evenly sprinkle the last 1 cup of shredded sharp cheddar cheese and 1 cup of shredded Monterey Jack cheese over the top. Bake for 25-30 minutes, or until bubbly and the cheese is melted and lightly golden. Broil for 2-3 minutes if desired for an extra-crispy crust, watching carefully.
Step 10: Remove from oven and let rest for 5-10 minutes before serving. Garnish with fresh chopped parsley and optional chopped dill pickles. Sprinkle remaining crumbled bacon on top. Enjoy!