In a large skillet with a lid or Dutch oven, heat 1/4 cup EVOO. Add the chicken thighs to the hot pan and brown on both sides, about 2 minutes per side. Remove them to a plate and reserve.
Add the pancetta and cook until crispy, about 2 minutes, then add the orzo and cook until brown and toasted. Add the mushrooms, carrot, onion and garlic, and cook about 5 minutes to soften. Add the rosemary and tomato paste, cook 1 minute, then add the white wine to deglaze the pan, scraping up all the little brown bits off the bottom of the pan.
Stir in the chicken stock and rice. Add the chicken back into the pot, cover and reduce the heat to low. Simmer about 15-18 minutes, until rice is just tender. Top with parsley and shaved Parmigiano Reggiano.