Step 1: Roast the Garlic : Preheat oven to 400°F (200°C). Slice off the top of the garlic bulb to expose the cloves. Drizzle with olive oil, wrap in foil, and roast for 30–35 minutes until soft and golden. Let it cool, then squeeze the roasted cloves from their skins and mash into a smooth paste.
Step 2: Cook the Pasta : Boil the jumbo shells in salted water until al dente (about 9–10 minutes). Drain and toss with a little olive oil to prevent sticking.
Step 3: Make the Alfredo Sauce : In a saucepan over medium heat, melt the butter. Whisk in flour and cook for 1–2 minutes until lightly golden. Gradually whisk in cream and milk, stirring constantly. Add the roasted garlic paste, Parmesan, salt, pepper, and nutmeg. Simmer until thick and creamy, about 5–6 minutes.
Step 4: Prepare the Filling :In a mixing bowl, combine shredded chicken, ricotta, mozzarella, and chopped herbs. Stir in ½ cup of the Alfredo sauce to moisten the mixture.
Step 5: Assemble the Shells :Preheat oven to 375°F (190°C). Spread ½ cup of Alfredo sauce on the bottom of a baking dish. Stuff each pasta shell with the chicken mixture and place in the dish. Pour the remaining Alfredo sauce evenly over the shells. Sprinkle mozzarella and Parmesan on top.
Step 6: Bake : Cover with foil and bake for 20 minutes. Remove foil and bake for another 10–15 minutes, until bubbly and golden.