1. Cut the eggplants into slices about 1 cm thick, then into cubes.
Place them in a microwave-safe dish and cover with plastic wrap. Cook in the microwave at full power for 10 minutes (for a power of 850 W).
2. Meanwhile, sauté the onions in a large skillet with olive oil.
3. When the eggplants are cooked, add them to the onions, then pour in the tomato sauce, season with salt, pepper (you can also add some Herbes de Provence), and sauté everything for 5 minutes over medium heat.
4. Grease the bottom of a rectangular dish with a paper towel soaked in a little olive oil, then line it with a first layer of 3 lasagna sheets.
5. Pour half of the mixture over the lasagna sheets, then drizzle with 1/3 of the cream. Repeat the process: layer of lasagna sheets, mixture, and cream. Finish by sprinkling everything with a little grated emmental cheese.
6. Bake in the oven at 200°C (392°F) for about 20 minutes, for a convection oven.