Chop off the green part and the root of the leek, discard. Split white part in half and wash well. Slice it finely.
Slice mushrooms.
Wash spinach and drain in salad spinner (if you have one. If you don't, you should!). Chop it coarsely.
Heat 2 tablespoons ghee or butter in a large pan. Add leek and mushrooms, cook for approximately 5 minutes. Add spinach, let it wilt and turn off stove.
Chop ham in 1-centimetre cubes.
Whisk eggs and season with salt and pepper. Mix in the veggies and ham.
Melt the other tablespoon of ghee or butter and grease the bottom of a large Pyrex baking tray. Pour the quiche mixture and bake until set, 40 - 50 minutes.
Cut in portions and serve, or keep in the fridge/freezer for later.