Heat olive oil in a large frying pan over moderate heat.
Fry the mushrooms until golden, add spinach and garlic cook for 1 - 2 minutes.
Break the eggs into a large bowl and whisk them together. Stir in grated cheese, mushrooms and spinach. Season and mix well.
Arrange sourdough slices onto a baking tray, spoon the mushroom, spinach and egg mixture over the bread and place into a hot oven for 15 minutes until crisp and golden.