1. Preheat the oven to 230C.
2. Heat the oil in a large frying pan. Add the mushrooms and onions and stir briefly. Cover the pan and cook for 3 minutes. Remove the cover and cook for 5 minutes longer, or until almost all the liquid boils off. Add the salt and remove from the heat.
3. Spread the pasta sauce on the pizza bases and sprinkle with the cheeses. Top with the mushrooms and onions.
4. Bake for 25 minutes, or until the crust is lightly browned and the cheese is bubbly. Cut into 8 slices.
Calories 385, Kilojoules 1,617, Total Fat 16 g, Saturated Fat 6.5 g, Sodium 937 mg, Carbohydrate 34 g, Dietary Fibre 2 g, Protein 21 g