In a large saucepan, heat olive oil over medium heat. Add onion and sauté until translucent. Add rice and sauté 2 minutes. Add wine and sauté an additional 2 minutes, or until liquid is absorbed. Stir in broth and bring to a boil.
Reduce heat to low, stir, and allow mixture to simmer for 10 minutes, or until it starts to thicken. Stir in spinach, 2 tablespoons of cheese and salt and pepper. Simmer 2 minutes longer. Transfer to a 2-quart casserole dish. Sprinkle remaining cheese over top and bake 35 minutes.