In a pot over medium-high heat, add olive oil, butter, and chopped onion. Sauté the onion for 3-4 minutes until it becomes translucent.
Stir in the minced garlic and orzo. Cook for 2-3 minutes, stirring occasionally to infuse flavor and lightly toast the orzo.
Pour in the chicken broth. Once it starts to bubble, cook uncovered for 10 minutes, stirring frequently. Adjust heat to medium or medium-low to maintain a gentle bubble. If necessary, add more broth to prevent excessive reduction before the pasta is cooked.
Stir in the softened Boursin cheese until smooth, ensuring the sauce is creamy and well combined.
Remove the pot from heat and add the spinach and chicken. Cover the pot for 5 minutes to allow the spinach to wilt, the chicken to heat through, and the sauce to thicken slightly.
Season with salt and pepper to taste. Serve with chopped chives sprinkled on top if desired for a fresh touch.
Notes
For a vegetarian option, substitute chicken with chickpeas or tofu for added protein.