Preheat your oven to 350°F (175°C).
Cook the macaroni according to package directions until al dente. Drain well.
Prepare the BBQ chicken using your preferred method (slow cooker, Instant Pot, or stovetop).
For the slow cooker method: Place chicken breasts in the slow cooker. Whisk together BBQ sauce, apple cider vinegar, smoked paprika, garlic powder, and onion powder. Pour over chicken. Cook on low for 6-8 hours or high for 3-4 hours. Shred with two forks.
For the Instant Pot method: Place chicken breasts in the Instant Pot. Mix BBQ sauce, apple cider vinegar, smoked paprika, garlic powder, and onion powder. Pour over chicken. Cook on high pressure for 8-10 minutes, followed by a 10-minute natural pressure release. Shred.
For the stovetop method: Season chicken breasts with salt, pepper, garlic powder, and onion powder. Sear in a skillet over medium-high heat until browned on both sides. Add the BBQ sauce mixture, reduce heat to low, cover, and simmer for 15-20 minutes, or until cooked through. Shred in the skillet.
Melt the butter in a large saucepan over medium heat.
Whisk in the flour and cook for 1-2 minutes, stirring constantly to create a roux.
Slowly whisk in the milk, about 1/2 cup at a time, making sure each addition is fully incorporated before adding more.
Continue whisking until the sauce is smooth and starts to thicken slightly (about 5-7 minutes).
Reduce the heat to low.
Add the salt, pepper, and garlic powder.
Gradually add the shredded cheese, one handful at a time, stirring continuously until the cheese is completely melted and the sauce is smooth and creamy.
Add the cooked macaroni to the cheese sauce in the saucepan. Stir to coat the macaroni evenly with the cheese sauce.
Gently fold in the shredded BBQ chicken, distributing it evenly.
Pour the mac and cheese mixture into a lightly greased 9x13 inch baking dish.
If desired, sprinkle extra shredded cheese on top.
Bake for 20-25 minutes, or until the top is bubbly and golden brown.
Let the mac and cheese cool for a few minutes before serving.
Garnish with your favorite toppings (chopped green onions, crispy bacon bits, extra BBQ sauce).
Serve immediately and enjoy!