- Pre-heat the oven to 200°C / 180°C Fan / 400°F / Gas Mark 6.
- Slice 1 of the onions and sweat in olive oil with the garlic and mixed herbs
- Cut the mushrooms into quarters and add to the pan along with the peas, spinach and chopped tomatoes then season to taste.
- Place in a suitable deep sided dish and top with thinly sliced potatoes and onions.
- Brush with a little vegetable oil and bake for 30 mins in the oven until the top is nice and brown.