Preheat the oven to 180°C and lightly grease a 23cm pie dish.
Combine the rice and egg and using the back of a spoon, smooth into the pie dish. Bake for 20 minutes.
Heat the oil in a large deep frying pan and cook the onion for 3 minutes, then add the mushrooms and cook for another 3 minutes, until soft. Add the spinach and stir through until wilted slightly.
Arrange half the feta into the pie shell, and top with the pumpkin. Spread the onion mixture over the top, then the remaining feta. Pour the eggs over, and nestle the tomatoes, cut side up, into the filling. Bake for 45 minutes, until set and golden. Stand for 5 minutes, before cutting into wedges to serve.