Preheat the oven to 180℃/355℉.
Bring a large saucepan to a medium-high heat. Add 1 tbsp ghee or fat of choice and add the chicken breasts. Cook for about 8 minutes without flipping (5 minutes for thin-cut breasts). Flip the chicken and then cook on the second side until well browned and cooked through (internal temperature of 75℃/165℉). Set aside and allow to rest while you prepare the gravy.
In the same pan, on a medium-high heat, add the remaining ghee, diced onion and diced carrots and sauté until the onions are translucent and slightly browned.
Add the garlic, thyme, salt, white pepper, and onion powder. Sauté for another 2-3 minutes.
Add in the flour and mix until the flour has absorbed all of the moisture and continue sauteing for another minute or so to remove the floury taste but do not burn the flour. Pour in the warm chicken stock *see notes. Stir until the sauce has thickened.
Add in the frozen peas and cream and stir until well combined. Slice the rested chicken breasts and add the chicken to the gravy as well as any juice from the rested chicken.
Finish off with the remining tsp of salt, if needed, and pour in to an ovenproof dish ( 30cm L x 24cm W x 5cm H).