Preheat oven to 375 degrees F.
Pat the chicken thighs dry with a paper towel.
Combine the salt, ground mustard, garlic powder, paprika, dried thyme, dried oregano, and black pepper in a bowl. Stir till combined.
Sprinkle the spice mixture over both sides of the chicken thighs.
Heat the olive oil in a large Dutch oven, skillet, or pot that is oven-safe and has a lid. Once hot, add the chicken thighs and cook for 3 to 4 minutes on each side until browned.
Remove the chicken and set aside.
Add the onion to the pan and cook for 4 minutes, till translucent. Then add the garlic and cook for 30 seconds, stirring continuously.
Add the artichokes, rice, chicken stock, lemon juice, lemon zest, and spinach to the pan. Stir to combine.
Nestle the chicken breasts into the rice mixture and cover the pan. Place in the oven and bake for 30 minutes.
Remove the pan from the oven and top with feta cheese and parsley. Serve immediately.