Cook the onions in a pan until golden then add spinach until wilted. Pour in the eggs.
Then cook until the eggs are set around the sides, using a spatula around the edges to carefully loosen it, making sure they aren’t sticking.
Finally, once the eggs have set around the perimeter and the center is just a little bit jiggly, pop the pan into the oven under the broiler for 3-5 minutes for the top to get a nice golden brown color.