Preheat the oven to 350. Spray an oven-proof 10” skillet with cooking spray.
Saute the baby spinach and mushrooms in the olive oil until soft. Arrange them evenly in the skillet.
Pour beaten eggs over vegetable mixture, top with cheese. Cook on stovetop just until eggs begin to set around the edge of the skillet.
Place the skillet in the oven and bake for 15 minutes or until the eggs are done and cheese is melted.
Divide into two pieces, serve.