Heat a large skillet over medium high heat and drizzle enough olive oil to lightly coat the bottom of the pan. Add the mushrooms and cook, undisturbed, for about 3 minutes, until golden, then stir to turn and continue to cook for another 3 to 5 minutes, until juices release and mushrooms are completely brown. Season with salt and pepper and add to the farro. Drizzle a bit more olive oil in the pan and add the shallots and garlic. Cook for another few minutes, then add in the spinach and parsley, cooking just to wilt. Season with the vegetables with salt and pepper, then add the vegetables to the farro mixture. Stir everything together and taste for seasoning, adding additional olive oil, salt and pepper if needed.