Drizzle 1 tablespoon oil in the base of your slow cooker.
Season chicken with salt and pepper, then sear in a separate hot skillet with the other 1 tablespoon oil, 2–3 minutes per side until golden (optional but adds tons of flavor).
Transfer chicken to the slow cooker. Add garlic, mushrooms, thyme, oregano, salt, pepper, and chili flakes. Scatter in sun-dried tomatoes.
In a medium bowl, whisk together bone broth and coconut milk until smooth. Pour over chicken.
Cover and cook on Low for 4–5 hours, or High for 2–3 hours, until chicken is tender and fully cooked through.
Whisk ½ tablespoon arrowroot with 2 tablespoons water in a small bowl until smooth, to make a slurry.
About 20 minutes before serving, stir the slurry + Parmesan (or 3 tablespoons nutritional yeast for dairy-free) into the slow cooker.
Turn to High, keep the lid slightly ajar, and cook another 15–20 minutes until thickened and creamy. Stir once or twice.
Once done, top with fresh basil and serve with your favorite sides – like the broccolini, rice, and/or mashed potatoes I mentioned in the skillet variation.