Preheat your oven to 350° F. Spray a muffin tray with olive oil.
In a large bowl beat your eggs well. Mix in the feta, baking powder, salt and pepper to taste. Add sriracha sauce if you like. Lastly fold in the baby spinach. Fill up 7 of the muffin slots with the mixture and bake for 20-25 minutes or until golden brown on top.