Preheat oven to 200C. Grease a 7-cup capacity baking dish.
Heat oil and butter in a frying pan over high heat. Add mushrooms and cook, stirring often, for 8 minutes or until golden. Reduce heat to medium and add onions and capsicum. Cook for 4 minutes or until tender. Transfer to a bowl and cool
Using a vegetable peeler, run blade down length of zucchini forming ribbons. Line prepared baking dish over base and sides with zucchini, overlapping slightly. Place ham into base of dish over zucchini.
Whisk eggs and add vegetables and feta. Season with salt and pepper. Pour mixture into baking dish, spreading evenly. Place tomato halves over bake, cut side up. Bake for 40 minutes or until golden and set. Serve with salad greens.