Preheat your oven to 200°C (fan 180°C / 400°F / Gas Mark 6). Bring a large pot of salted water to a rolling boil. Add the pasta and cook for 2 minutes less than the packet suggests — the pasta should still have a firm, white core when you bite into it. Drain it in a colander and set aside. You will hear the pasta clatter against the colander as it drains.

While the pasta cooks, heat the olive oil in a large frying pan over a medium-high heat. Add the chicken chunks in a single layer. Do not stir for the first 3 minutes — let the chicken develop a golden-brown crust. You will hear a steady sizzle as the meat sears. Once the underside is deep golden, flip each piece. The cooked side should look caramelised and smell nutty.

Add the chopped onion to the pan and stir it through the chicken. Cook for 3 minutes until the onion softens and turns translucent. The raw onion smell will fade, and a sweet, savoury aroma will take its place. Add the minced garlic and cook for 30 seconds, just until fragrant — burnt garlic tastes bitter, so keep it brief.

Sprinkle the flour over the chicken and onions, then stir for 1 minute. This cooks out the raw flour taste and helps thicken the sauce later. The mixture will look slightly pasty and dry — that is exactly what you want.

Pour in the chicken stock gradually, stirring constantly. The liquid will bubble and steam as it hits the hot pan. Once the stock is fully incorporated, add the double cream and the basil pesto. Stir until the sauce is smooth and a pale, speckled green colour. Let it simmer gently for 2 minutes — you will see the sauce thicken slightly and coat the back of a spoon.

Add the drained pasta directly into the sauce and stir well with tongs or a pasta fork until every piece is coated. The pasta will look glossy and smell richly of basil and cream. Season with salt and pepper to taste. Transfer the entire mixture to a large baking dish (about 30cm x 20cm).

Sprinkle the grated mozzarella and Parmesan evenly over the top. Bake in the preheated oven for 15-18 minutes, until the cheese is melted and bubbling with golden-brown spots. The top should be crispy in places and the sauce will be bubbling up around the edges. Let it rest for 5 minutes before serving — this allows the sauce to settle so it does not run all over the plate.