Start with one tlbsp of coconut oil in an oven safe skillet and add onions until softened, then add the mushrooms and cook til soften a bit.
Add more coconut oil as needed.
Add tomatoes and also cook till soft and then add the spinach and stir until wilted.
Whisk the eggs and add to the skillet and cook on medium, pulling the eggs away from the sides toward the center. Then let cook and watch until there isn't too much liquid left and the sides are set and you can lift to see the bottom is getting brown.
Put the cheese on top and place under the broiler with rack the second level from the flame, until the cheese is melted and browned. Remove from broiler.
Put a knife into center and if still wet, put back on stovetop burner and cook a little more.
Cool for 10 minutes, run a knife around the edge and place a large plate on top a flip. Cut into 8 large or 12 smaller pieces and serve. Can be refrigerated and warmed in microwave.