Bring a large pot of salted water to a rolling boil. Add the fettuccine and cook according to package directions until al dente — about 10 to 11 minutes. The pasta should feel firm to the bite but not chalky in the centre. Reserve about a cup of the starchy pasta water before draining; that golden, cloudy liquid is liquid gold for the sauce.

While the pasta cooks, prepare the chicken. Place each chicken breast between two sheets of cling film and gently pound to an even thickness of about 2cm. Season both sides with a pinch of salt and pepper. The meat should feel uniformly flat under your fingers, ensuring it cooks evenly without dry edges.

Heat the olive oil in a large frying pan over medium-high heat. When the oil shimmers and a drop of water sizzles on contact, lay the chicken breasts in the pan. Cook for 5 to 6 minutes on the first side, until the underside is a deep golden brown and releases easily from the pan. Flip and cook for another 4 to 5 minutes. The chicken should feel firm to the touch and the internal temperature should reach 74°C. Transfer to a cutting board and let it rest for 5 minutes — you'll hear a faint sizzle as the juices settle.

Reduce the heat to medium-low and add the butter to the same pan. Once it melts into a foamy, nutty puddle, add the minced garlic. Stir for about 30 seconds until the kitchen smells fragrant and the garlic softens but does not brown. The butter should look pale and bubbly.

Pour in the double cream, stirring constantly with a wooden spoon. Scrape up any browned bits from the bottom of the pan — those little flecks carry immense flavour. Let the cream simmer gently for 2 minutes; you'll see it thicken slightly and the colour deepen to a warm ivory.

Remove the pan from the heat and add the grated Parmesan. Stir vigorously in one direction until the cheese melts completely into the cream. The sauce should be smooth and glossy, coating the back of a spoon. If it seems too thick, add a splash of the reserved pasta water to loosen it. Season with salt, pepper, and nutmeg if using.

Thinly slice the rested chicken against the grain. The slices should be about 1cm thick, revealing a moist, white interior. Add the drained fettuccine to the sauce, toss gently with tongs until every strand is coated, then arrange the chicken slices on top. Garnish with fresh parsley and serve immediately.