Preheat and Prepare: Preheat your oven to 180°C (160°C fan). Lightly grease a 9x13 inch (or similar 2.5-litre) baking dish.

Cook the Pasta: Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions, but undercook it by about 2 minutes so it's very 'al dente'. It will finish cooking in the oven. Drain the pasta, reserving about 250ml of the starchy cooking water.

Start the Sauce: While the pasta is cooking, melt the butter in a large saucepan or Dutch oven over medium heat. Add the minced garlic and cook for about 1 minute until fragrant, being careful not to let it brown.

Build the Cream Sauce: Pour in the double cream and whole milk. Bring the mixture to a gentle simmer, stirring occasionally. Let it simmer for 2-3 minutes to thicken slightly. Reduce the heat to low.

Add the Cheese: Remove the saucepan from the heat. Gradually stir in the 120g of freshly grated Parmesan cheese until it has completely melted and the sauce is smooth. What works best for me is adding the cheese in three batches to ensure it incorporates without clumping. Season with salt, pepper, and the ground nutmeg. If the sauce seems too thick, you can stir in a splash of the reserved pasta water.

Combine Everything: Add the drained pasta and the cooked, shredded chicken (if using) to the saucepan with the Alfredo sauce. Gently stir until everything is evenly coated in the creamy sauce.

Assemble the Bake: Pour the pasta mixture into your prepared baking dish and spread it into an even layer.

Top and Bake: Sprinkle the grated mozzarella and the extra Parmesan cheese evenly over the top. Cover the dish with aluminium foil.

Bake to Perfection: Bake for 15 minutes, then remove the foil and continue to bake for another 10-15 minutes, or until the top is golden brown and the sauce is bubbling around the edges.

Rest and Garnish: Let the baked alfredo rest for 5-10 minutes before serving. This allows the sauce to set up slightly. Garnish with freshly chopped parsley and serve warm.