In a saucepan, warm the chicken stock on a low heat.
In another larger saucepan heat the olive oil and butter then saute the onion until softened.
Add the rice and stir to coat. Once the rice has turned a pale golden colour add white wine, stirring continuously until absorbed. Add half the mushroom and stir through.
Add a ladle of chicken stock to the rice stirring continuously until absorbed. Repeat adding a ladle of chicken stock at a time until the liquid is absorbed.
When the rice is almost done stir in the remain mushrooms, spinach, cheese, salt and pepper.