Bring a large pot of salted water to a rolling boil and cook the elbow macaroni to 1 minute shy of package instructions (usually 7–8 minutes for al dente). Salt the water generously so the pasta is seasoned from the inside out; cooking it slightly under prevents over-softening when baked with the sauce.

While the pasta cooks, pat the chicken dry and season both sides with 1 tsp kosher salt, 1/2 tsp black pepper, and 1 tsp smoked paprika. Drying the surface ensures a better sear which creates Maillard browning — that deep, savory flavor foundation.

Heat 1 tbsp olive oil in a large sauté pan over medium-high heat until shimmering. Sear the chicken 3–4 minutes per side until deeply golden (internal temp ~155°F/68°C). Searing on higher heat develops a caramelized crust and locks flavors into the meat. Remove to a plate and tent loosely with foil; it will finish cooking in the oven and with the BBQ glaze.

In the same pan (do not wipe clean — the fond is flavor), lower heat to medium and add 1 tbsp butter. Add the diced onion and sauté until translucent, about 4 minutes; this softens the onion and releases sweet flavors. Add the minced garlic and sauté 30–45 seconds until aromatic — garlic cooks quickly and can burn.

Make the roux: in a medium saucepan melt 3 tbsp butter over medium heat, whisk in 3 tbsp flour and cook 60–90 seconds. Cooking the flour tastes reduces the raw flour flavor and gives the sauce a toasty backbone — don’t let it brown too much or it will taste nutty rather than neutral.

Slowly whisk in 3 cups of whole milk, a little at a time to avoid lumps. Bring to a gentle simmer while whisking constantly; simmer 2–3 minutes until the sauce thickens enough to coat the back of a spoon. Gentle simmering cooks the starch and concentrates the dairy flavor — avoid a rolling boil which can split the sauce.

Turn off the heat and stir in the shredded cheddar, smoked gouda, grated Parmesan, 1 tsp Dijon mustard, and the sautéed onion + garlic. Stir until cheeses melt and the sauce is silky. Doing this off direct heat prevents the cheese from seizing and becoming grainy.

Taste and adjust seasoning with salt and pepper. If the sauce is too thick, whisk in up to 2 tbsp warm milk; if too thin, simmer very gently a minute longer. Balance is key: the cheddar brings sharpness, the gouda brings smoke and creaminess, and Dijon brightens the dairy.

Drain the pasta and return to the pot. Cut the seared chicken into 1–inch pieces and toss with 1/2 cup of the BBQ sauce mixed with the 2 tbsp honey and 1 tbsp vinegar (optional). The vinegar helps cut the honey sweetness and sharpens flavor. Reserve an extra 1/4 cup BBQ sauce for finishing drizzle.

Fold the cheese sauce into the drained pasta until evenly coated, then gently fold in the glazed chicken pieces. Combining off heat preserves sauce texture and keeps chicken juicy; use a rubber spatula to avoid breaking pasta.

Preheat the oven to 400°F (200°C). Transfer the mac and cheese + chicken to a 9x13-inch baking dish and smooth the top. This baking step melds flavors, crisps the top, and warms the chicken through evenly.

Mix the panko with 2 tbsp melted butter and a pinch of salt, then sprinkle evenly over the mac. Dot with a small extra sprinkle of smoked paprika if you like. The buttered panko will brown quickly and add a toasted crunch that contrasts the creamy interior.

Bake 12–15 minutes until bubbly and the topping is golden brown. If you want extra crunch, switch the oven to broil for 1–2 minutes—watch carefully to avoid burning. Let rest 5 minutes; resting lets the sauce thicken slightly for clean slices.

Before serving, drizzle the reserved 1/4 cup BBQ sauce over the top and sprinkle chopped parsley for color and freshness. The finishing BBQ drizzle sharpens the BBQ identity and the herb lifts the richness.