First, cook the pasta in a large pot of salted boiling water until al dente according to the package instructions. Before draining, reserve about 1 cup of the pasta cooking water, then drain the pasta and set it aside.
Next, season the sliced chicken breast with salt and black pepper. Heat 1 tablespoon of butter or olive oil in a large skillet over medium-high heat, then cook the chicken for 5–7 minutes until golden brown, lightly caramelised, and fully cooked. Remove it from the pan and set it aside.
Then, reduce the heat to medium and add the remaining butter or olive oil to the same pan. Stir in the gochujang, soy sauce, and honey, cooking for 1–2 minutes while stirring continuously to develop a rich, bold flavour.
Afterwards, pour in the heavy cream along with a splash of the reserved pasta water. Stir well until the sauce becomes smooth, creamy, and silky. Add a little more pasta water if needed to loosen the sauce.
Next, return the cooked chicken and drained pasta to the skillet. Toss everything together for 1–2 minutes until the pasta is evenly coated in the creamy gochujang sauce and the chicken is thoroughly heated.
Finally, stir in the grated Parmesan cheese if using, then taste and adjust the flavour by adding extra honey for sweetness or more gochujang for additional heat. Serve immediately while hot and garnish with extra Parmesan, spring onions, or sesame seeds if desired.