Preheat oven to 400 degrees Fahrenheit.
Brush the outsides of the mushrooms with olive oil and place, stem side up, on a cookie sheet lined with Gefen Parchment Paper and drizzle with balsamic vinegar. Roast in the oven till the mushrooms are soft, about 10–15 minutes, and set aside.
Add oil to a sauté pan, allow oil to heat up, and then add the onion and sauté until soft. Add garlic cloves, and sauté for another two minutes. Then add spinach, and season with salt and pepper to taste and continue to cook for another 10 minutes until the flavors concentrate.
Add in the chopped nuts, and mix.
Divide the mixture into the prepared mushrooms and bake at 400 degrees Fahrenheit for 10 minutes.
Photography: Hudi Greenberger.
Styling: Renee Muller.