Preheat your oven to 200°C (fan 180°C). Bring a large pot of salted water to a rolling boil. Add the pasta and cook for 2 minutes less than the packet instructions suggest — it should still feel firm and white in the centre when you bite into it. Drain the pasta, reserving about 100ml of the starchy pasta water.

While the pasta cooks, prepare the creamy buffalo sauce. In a large mixing bowl, beat the softened cream cheese with a wooden spoon until it's smooth and glossy, with no visible lumps. Pour in the double cream and chicken stock, then whisk until the mixture is completely combined and has a pale, silky consistency. Stir in the buffalo hot sauce, garlic powder, onion powder, salt, and pepper. The sauce will smell tangy and slightly spicy at this stage.

Combine the chicken and jalapeños. Add the shredded chicken and diced jalapeños to the sauce bowl. Fold everything together gently with a spatula until every piece of chicken is coated. You'll see flecks of green jalapeño and orange hot sauce throughout the creamy mixture.

Add the pasta and half the cheese. Tip the undercooked pasta into the bowl and stir until the sauce clings to every piece. The pasta should look glossy and well dressed. Fold in half of the grated mozzarella and half of the cheddar cheese, reserving the rest for the top.

Transfer to your baking dish. Pour the entire mixture into a 9x13 inch baking dish and spread it into an even layer with the back of your spoon. The surface should be relatively flat. Sprinkle the remaining mozzarella and cheddar evenly over the top — you want a generous, even blanket of cheese. If the mixture looks a little dry, drizzle in a tablespoon of the reserved pasta water.

Bake until golden and bubbling. Place the dish on the middle rack of your oven and bake for 20-25 minutes. Around the 15-minute mark, you'll hear the sauce start to bubble and see the cheese melting and turning a pale gold. The casserole is ready when the edges are bubbling vigorously, the top is golden brown in patches, and the cheese is completely melted with a slight crust. A knife inserted into the centre should come out hot to the touch.

Rest and garnish. Remove the dish from the oven and let it sit on the counter for 5 minutes. This resting time allows the sauce to thicken and set slightly — you'll see it stop bubbling and become creamier. Sprinkle the sliced spring onions and fresh coriander over the top just before serving. The bright green garnish contrasts beautifully with the golden, cheesy surface.