Pat chicken pieces dry and season with salt, pepper, and oregano. Heat olive oil and butter in a large skillet over medium-high heat. Add the chicken and cook until golden brown and cooked through, about 3-4 minutes per side. Remove chicken and set aside.

In the same skillet, add the chopped onion and cook until softened, about 3-4 minutes. Add the minced garlic and cook for 1 minute more until fragrant.

Add the dry orzo to the skillet and stir for 1-2 minutes to toast. Pour in the chicken broth, scraping up any browned bits. Bring to a simmer.

Reduce heat to low, cover, and cook for 10-12 minutes, or until orzo is al dente and has absorbed most of the liquid.

Turn off the heat. Crumble in the Boursin cheese and stir until it melts into a creamy sauce. Stir in the fresh spinach until it wilts.

Return the cooked chicken to the skillet and stir to combine. Serve immediately.