Bring the broth to the boil, stir in the green spelled, remove from the heat and let it swell, covered.
Halve the aubergines lengthways and hollow them out so that there is an approx. 8 mm thick edge all around. Finely dice the pulp. Peel and finely chop the onion, cut the mushrooms into slices.
Heat the butter in a pan. Sauté the onion pieces, mushroom slices and aubergine cubes for about 5 minutes, stirring occasionally. Meanwhile preheat the oven to 200 ° C top / bottom heat.
Pour the swollen green spelled meal into the pan with the vegetables, mix in briefly, season the mixture with salt and pepper and cook for another 2 minutes. Meanwhile, dice the tomatoes, then mix with the cheese into the green spelled mixture.
Distribute the mixture evenly in the hollowed out aubergines. Sprinkle with the grated cheese and bake in the preheated oven for about 20 minutes. Serve hot.