Caramelize the onions: Heat a large skillet over medium heat and add 2 tablespoons of butter and 1 tablespoon of olive oil. Add the sliced onions, a pinch of salt, and cook slowly for 15-20 minutes, stirring occasionally until they turn golden brown and sweet. Patience is key here; don’t rush it.
Prepare the chicken: While the onions are caramelizing, season the chicken thighs with salt, pepper, and half the thyme.
Brown the chicken: Push the caramelized onions to the side of the skillet and add the remaining olive oil. Place the chicken in the pan, skin-side down if using thighs with skin. Sear each side for 3-4 minutes until golden brown.
Add garlic and rice: Mix in the minced garlic with the onions, sauté for 30 seconds until fragrant, then stir in the rinsed rice. Let it toast slightly for 2 minutes—it adds a subtle nuttiness.
Pour in the broth: Slowly add 2 ½ cups of chicken broth. Stir everything together, making sure the rice is evenly distributed and submerged in the liquid. Bring to a gentle boil.
Simmer and cover: Reduce the heat to low, cover the skillet, and let it simmer for 20 minutes. Avoid lifting the lid too often; this helps the rice absorb the liquid fully.
Optional cheesy finish: If you’re adding Gruyère, sprinkle it on top during the last 5 minutes of cooking and cover until melted.
Garnish and serve: Remove from heat, let it sit for 5 minutes, then sprinkle with fresh parsley. Scoop generous portions onto plates and enjoy the comforting flavors.