Wash the aubergines, slice lengthwise, sprinkle with salt and leave to stand for 10 minutes. Peel, wash and finely dice celery and carrots. Peel onion and garlic. Peel onion, press garlic through a garlic press.
Remove the marjoram leaves and chop half of them very finely. Dab aubergine slices dry and turn in flour. Fry the aubergine slices in 6 tablespoons of hot oil in portions on each side for about 2 minutes, remove.
Add 2 tablespoons of oil to the frying fat and fry the onion and garlic in it until transparent. Stir in tomato paste, add celery and carrots and steam everything briefly. Season with salt, pepper and paprika. Add tomatoes, vegetable stock and chopped marjoram, bring to the boil and simmer for 5 minutes at low heat.
Cut olives into thin rings and fold in. Season sauce again. Crumble the feta finely. Grease casserole dish. Fill in 1/3 of the eggplant slices, bacon and 1/3 of the tomato sauce one after the other. Sprinkle with 1/3 of the cheese.
Layer the rest of the aubergines, tomato sauce and cheese in the same way. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3/ convection oven 175 °C) for 20-30 minutes. Sprinkle with marjoram leaves before serving.