Lightly fry the onion in a bit of butter and olive oil until it is clear. Add the raw rice and stir until the rice is coated with oil.
Start adding the chicken stock, a little at a time, and stir as it is absorbed by the rice. Meanwhile, saute the chicken in a little oilve oil in a separate pan until browned. Add salt and pepper to taste and the garlic.
When the rice is just about done, add the chicken, the spinach and the sundried tomatoes to the rice. Cook, stirring, for a final two minutes. Finish it off with a teaspoon of butter and serve with parmesan cheese.