In a large frying pan, heat a drizzle of butter or oil over medium heat. Add the chopped onions with a pinch of salt and sauté for about 7 minutes, or until softened and golden. Remove the onions from the pan and set them aside.
Coat the chicken thighs evenly with the French onion soup mix. In the same frying pan, heat 3 tablespoons of olive oil over medium-high heat. Sear the chicken for about 2 minutes on each side, until golden brown. Remove the chicken from the pan and set it aside.
In the same pan, add the long-grain rice and cook for 1 minute, stirring to coat the rice in the pan’s residual flavors. Add the chicken stock, sour cream (or your choice of cream), and a pinch of salt. Stir and bring to a gentle simmer, allowing it to cook for 3-4 minutes.
Return the cooked onions, spinach leaves, and seared chicken thighs to the pan. Stir gently to combine. Cover the pan and simmer over low heat for 20-25 minutes, or until the rice is tender and the chicken is cooked through.
Once everything is cooked, season with salt and pepper to taste. Remove from heat and let it sit for a few minutes before serving.
