Cook the Pasta: Bring a large pot of well-salted water to a boil. Add the penne and cook according to package directions until al dente. Just before draining, reserve about 250ml (a mugful) of the starchy cooking water. Drain the pasta in a colander and set aside.

Sear the Chicken: While the pasta is cooking, heat 1 tbsp of olive oil in a large, deep frying pan or sauté pan over a medium-high heat. Season the chicken cubes with salt and pepper. Add the chicken to the hot pan in a single layer (cook in two batches if necessary to avoid overcrowding) and cook for 5-7 minutes, turning occasionally, until golden brown and cooked through. Remove the chicken from the pan and set aside on a plate.

Sauté the Aromatics: Reduce the heat to medium. Add the remaining 1 tbsp of olive oil and the butter to the same pan. Once the butter has melted, add the chopped onion and cook for 4-5 minutes until softened and translucent. Add the minced garlic and sliced jalapeños and cook for another minute until fragrant.

Create the Sauce Base: Pour in the chicken stock to deglaze the pan, scraping up any browned bits from the bottom with a wooden spoon. Let it bubble and reduce by about half, which should only take a minute or two.

Make it Creamy: Lower the heat and slowly pour in the double cream, stirring constantly. Allow the sauce to come to a gentle simmer – do not let it boil rapidly, as this can cause it to split.

Melt the Cheese: Remove the pan from the heat for a moment and add the grated cheddar and Parmesan. Stir continuously until the cheeses have completely melted into the cream, creating a smooth, velvety sauce. Season with salt and pepper to your taste. What works best for me is tasting at this stage, before the pasta is added, to get the seasoning just right.

Combine Everything: Return the cooked chicken and the drained pasta to the pan with the sauce. Toss everything together gently until the pasta and chicken are thoroughly coated. If the sauce seems too thick, add a splash of the reserved pasta water to loosen it to your desired consistency.

Serve Immediately: Divide the pasta among four warm bowls. Garnish with a sprinkle of fresh parsley and an extra grating of Parmesan cheese.