Preheat oven to 375° Fahrenheit.
Pat chicken thighs very dry. Season liberally with sea salt.
In oven-safe skillet, heat ghee or olive oil over medium-high heat until very hot. Using tongs, place chicken thighs skin-side down in skillet. Sear 5 minutes, or until skin is golden brown and no longer sticks to skillet.
Flip chicken thighs. Cook 2 minutes more on stovetop, then transfer skillet to preheated oven.
Roast chicken thighs 15 minutes or until internal meat thermometer reads approximately 162° Fahrenheit (not a typo). Carefully remove skillet from oven. Be careful: use potholders to handle skillet from this point forward.
Transfer chicken thighs to plate. Pour off all but 1-2 tablespoons fat from skillet. Return skillet to stove over medium-low heat.
Add onion to skillet. Sauté until translucent, approximately 5 minutes.
Add garlic and sauté, stirring constantly, for approximately 30 seconds.
Sprinkle in arrowroot starch, then pour in ½ cup coconut milk. Use whisk to loosen any browned bits on skillet and to incorporate arrowroot starch with milk.
Add remaining coconut milk, lemon juice, artichoke hearts, and spinach to skillet. Increase heat to medium.
Bring mixture to boil, then reduce heat and simmer 5 minutes or until thickened. Stir as needed to prevent sticking.
If needed, return chicken thighs to skillet long enough to warm through. Divide chicken thighs and spinach artichoke sauce evenly amongst 4 plates. Garnish with red pepper flakes and serve.