1. In a medium saucepan bring 4-5 cups of salted water to boil for the orzo.
2. Meanwhile, while orzo is cooking, start a skillet over medium heat for the mushrooms. Add 1 tablespoons of the olive oil, and 1 tablespoon butter, and 2 cloves of the garlic. Stir in the mushrooms and toss to coat. Let set and sauté until very browned and caramelized. Then flip until both sides re very caramelized.
3. when pasta is just about done, turn off the saucepan, and let set in the hot water until the mushrooms are ready. Reserve 1 ladle of the pasta water before draining.
4. Once the mushrooms are ready, add the remainder of the butter and olive oil to the pan, and if you like more garlic flavor add the remainder of the garlic now. Toss and cook a couple of seconds. Then add spinach, pasta and the pasta water if using to the skillet with the mushrooms, add green onions and mix well. Once warmed through add the cheese and serve.