Preheat the grill to medium-high and cook the bacon until browned on both sides.
Spray a small non-stick frying pan with oil and fry the sliced mushrooms for 5 minutes until soft.
Steam the rinsed spinach in the pan for 2 minutes, then squeeze out all excess water using a sieve.
Clean the pan, spray with oil, and fry the potatoes and tomatoes for 5 minutes until colored.
Beat the eggs in a bowl and stir in the chopped bacon, spinach, and cooked mushrooms.
Add the browned potatoes and tomatoes to the egg mixture, then pour everything back into the pan.
Cook gently for 10 minutes until edges are set, then grill for 2 minutes to finish the top.
Cool slightly before slicing into wedges and serving.