1. Preheat oven to broil. In a large oven-safe skillet, heat olive oil and butter over medium-low heat.

2. Add sliced onions and a pinch of salt. Cook, stirring occasionally, for 30-40 minutes until deeply caramelized. Add garlic in the last 2 minutes until fragrant. Remove onions from skillet and set aside.

3. Season chicken with salt, pepper, and dried thyme. Increase heat to medium-high, add a little oil if needed, and sear chicken until lightly browned. Remove and set aside.

4. Reduce heat to medium. Add uncooked orzo to the skillet and toast for about 1 minute, stirring constantly.

5. Pour in white wine to deglaze the pan, scraping up browned bits. Let simmer for 1 minute.

6. Stir in beef broth and Worcestershire sauce. Return chicken and caramelized onions to the skillet. Cover and simmer on low for 15-20 minutes, until orzo is tender.

7. Stir once, then sprinkle Gruyère and Parmesan evenly over the top. Transfer skillet to oven and broil 2-4 minutes until cheese is bubbly and golden. Garnish with parsley and serve.