1. **Roast the Garlic:** Slice the top off the garlic head to expose the cloves. Drizzle with 1 teaspoon olive oil, wrap in foil, and roast at 400°F (200°C) for 30–40 minutes until soft and golden. Cool slightly, squeeze out the cloves, mash, and reserve.

2. **Cook the Pasta:** Cook elbow pasta in salted boiling water according to package instructions. Drain, reserving ½ cup of pasta water, and return to the pot. Toss with 1 teaspoon olive oil to prevent sticking. Set aside.

3. **Sauté the Swiss Chard:** In a skillet, heat the remaining 1 tablespoon olive oil over medium heat. Add half of the minced garlic and sauté for 1 minute. Add chopped Swiss chard and cook for 2–3 minutes until wilted. Stir in lemon zest and juice. Season with salt and pepper. Reserve.

4. **Prepare the Cheese Sauce:** In the same skillet, melt ¼ cup butter over medium heat. Add the remaining minced garlic and cook for 1 minute. Stir in flour and cook until bubbly and golden. Gradually whisk in milk. Bring to a boil, then reduce to medium-low and stir constantly for 8–10 minutes until thickened. Stir in heavy cream, mashed roasted garlic, dry mustard, paprika, nutmeg, and season with salt and pepper. Cook for 3–5 minutes until thick and creamy.

5. **Combine Ingredients:** Add cooked pasta, Swiss chard mixture, and grated Gruyère cheese to the sauce. Stir until well combined. If needed, add reserved pasta water to reach desired consistency.

6. **Assemble and Bake:** Preheat the oven to 400°F (200°C). Butter a 9×13-inch baking dish. Transfer the mac and cheese mixture to the dish. In a bowl, combine Panko breadcrumbs, garlic powder, and melted butter. Sprinkle over the mac and cheese. Bake for 20–25 minutes, or until the top is golden brown and the sauce is bubbly. Garnish with chopped chives before serving.