In a medium saucepan combine both the chicken and beef broths. Bring to a broil, turn down heat to a simmer.
In a large saucepan heat oil, cook mushroom, onion and green beans until tender and lightly browned. Add rice, garlic, thyme and rosemary. Turn heat to medium high. Cook and stir for 2 to 3 minutes or until rice begins to brown. Add Marsala, cook and stir until Marsalla is absorbed.
Add 1/2 cup of the broth to the rice mixture, stirring constantly. Continue to cook and stir over medium high heat until broth is absorbed. Add another 1/2 cup of broth to the rice mixture, repeat the process 1/2 cup at a time until all the broth has been added to the rice and is absorbed ( this should take about 20 to 25 minutes). Turn the heat off and stir in the spinach. Keep stirring until the spinach is wilted.