Prepare the Portobello mushrooms by removing the stems and scraping out the gills with a spoon. Spray both sides of the mushrooms with cooking spray and place on a baking sheet.
Bake the mushrooms for 5 minutes. Pour out the liquid from each mushroom.
Reduce the oven heat to 400 degrees F.
Heat the olive oil in a medium skillet set over medium heat. Add the onions and cook until starting to brown, about 5 minutes.
Stir in the tomatoes and spinach. Cook until the spinach is just wilted, about 1 minute. Season with ground pepper and salt.
Divide the tomato mixture between the mushrooms, making an indentation in the middle of the mixture. Sprinkle the Gouda cheese over top.
Carefully crack an egg onto each mushroom, placing the yolk in the indentation.
Bake until the egg whites are set, about 10 minutes.
Garnish with parsley and serve.
Notes
Weight Watchers Points: 4 (Points+), 3 (Old Points)Note: Buy large portobello mushrooms that have a high sides. This will help to hold in the egg during baking.