Preheat oven to 180°C. Brush mushrooms with olive oil, inside and out. Wilt spinach in boiling water, drain and finely chop.
Transfer the spinach to a mixing bowl and add the remaining ingredients. Season with salt and pepper.Mix all filling ingredients together and stuff into mushroom caps.Bake for 15 – 20 minutes.
*use any preferred nut or a mixture of nuts such as, almond, macadamia, brazil nuts and pecan nuts.