Cut the eggplant into thin slices and pass it in the heated skillet with olive oil to soften a little and set aside.
In a pan, sauté the onion, tomato and sausage.
Add the sauce sachet and adjust the salt.
Place a little sauce on a baking sheet and place a few slices of eggplant, on top of which place slices of cheese and sauce.
Make layers until you end up with sauce and sprinkle with grated cheese.
Bake at 180° for 20 minutes or until the cheese melts.