Preheat the oven to 425ºF and line a baking sheet with parchment paper. Arrange the portobello mushroom caps on a parchment-lined baking sheet and season with salt and pepper. Bake for 10 to 15 minutes. Remove from the oven and soak up any excess liquid with a towel.
Meanwhile, heat a non-stick skillet over medium heat and add half the oil. Once warmed, add the spinach. Cook until wilted and then remove and set aside.
In a small bowl, whisk the eggs. In the same skillet, add the remaining oil. Pour in the eggs and stir with a wooden spoon until scrambled and cooked to your liking. Remove from the heat.
Layer the spinach in the mushroom caps and top with eggs, feta, salt, and pepper.
Slice some veggies for a side salad
Put on some dressing. Enjoy!