Butterfly the chicken breasts to open them up & slice each breast in half to create 4 fillets. Place them in a mixing bowl, add in the onion powder, garlic powder, olive oil & seasoning to taste. Mix well to combine.
Place a saucepan of water over high heat, bring to a boil, season generously with sea salt flakes & cook the pasta as per your packet instructions.
Place a large pan over high heat, add the clarified butter, allow it to melt. Add in the seasoned chicken breasts (in batches), sear for 3 minutes on both sides, remove & allow to rest for 5-10 minutes before slicing into thin strips. Cover & keep warm.
In the same pan, add in the diced onion & drained green peppercorns, saute for 3-4 minutes or until lightly golden & translucent. Add in the garlic & saute for 45 seconds, stirring the whole time.
Add in the wine or chicken stock, bring to a boil and cook stirring frequently until it reduces by half. Add in the cream & seasoning to taste, mix well, bring to a heavy simmer, reduce heat to low & simmer for 6-7 minutes or until reduced & thickened.
Place the sliced chicken into the sauce along with any resting juices. Transfer the cooked pasta straight from the pot into the sauce, reserving some pasta water if you wish to thin the sauce down. Add in the flat-leaf parsley & mix well to combine. Serve in bowls & garnish with flat-leaf parsley & Parmigiano Reggiano (optional).