Pat the chicken breast dry with a paper towel and season both sides evenly with sea salt and black pepper.
Heat the olive oil in a medium skillet over medium-high heat. Once hot, add the chicken and sear for 5-6 minutes per side until golden brown and cooked through to an internal temperature of 165°F.
Remove the chicken from the skillet and set aside on a plate to rest.
In the same skillet, add the sliced mushrooms and diced onions. Sauté for 5-7 minutes until the onions are translucent and the mushrooms have released their moisture and turned deep brown.
Add the minced garlic and fresh thyme leaves to the skillet, stirring for 1 minute until fragrant.
In a small bowl, whisk together the coconut milk, chicken bone broth, and arrowroot powder until no lumps remain.
Pour the liquid mixture into the skillet with the vegetables. Bring to a gentle simmer, stirring constantly, until the sauce thickens into a rich, creamy gravy.
Return the chicken breast to the skillet, spooning the mushroom gravy over the top to coat thoroughly before serving.