1. Cut the aubergine into 1/2 cm thick slices (16 slices).
2. Add salt on top and let them sit for a while, to remove the bitterness.
3. In a frying pan place a little oil and cook the onion cut into small pieces with a little salt, until golden brown.
4. Add the garlic and stir.
5. Use a pastry cutter or similar and cut out 8 circles of cheese. Set aside.
6. Wash the eggplant to remove excess salt and pat dry with paper towels.
7. Place a circle of cheese on a slice of eggplant, and on top of the cheese, a little of the onion with garlic.
8. Cover with another slice.
9. Repeat with all the slices until you form 8 medallions.
10. In a bowl, prepare a fake egg by mixing the chickpea flour, cornstarch, water, and mustard. It should have the texture of a beaten egg.
11. Make another bowl of breadcrumbs.
12. Dip each medallion first through the fake egg and then through the breadcrumbs.
13. Preheat the oven to 180°C/350ºF.
14. On a baking sheet, place a little cooking spray, and place the medallions, cooking for 15 minutes on each side.