Preheat oven to 350 degrees
Heat oil in a large skillet over medium-high heat
Add mushroom stems, onions, bell pepper.salt and pepper
Cook stirring occasionally until soft
Transfer to a large bowl, add spinach, mix well and set aside to cool
Arrange mushroom caps in a single layer on a parchment paper lined baking sheet
Add salt and pepper to spinach mixture, then divide filling evenly between mushroom, mounding it in the center of each
Drizzle lightly with remaining olive oil and bake until soft and juicy. Approx 20 minutes.
*Recipe and photo credits to ITG's Your Loss Your Gain in Illinois!