Heat the oven to 200°C (180°C in a fan oven), gas 6.
Rub the eggplants with two tbsp oil and bake for 45 minutes until soft.
Melt the butter in a pan and stir in the flour.
Gradually add the milk, stirring continuously.
Bring to the boil and then simmer for 10 minutes.
Add the cheese and season with salt, ground black pepper and lemon juice.
Remove from the heat.
Remove the eggplants from the oven, cut them in half, scoop out the flesh and chop roughly.
Heat the remaining oil and fry the onion, garlic and the eggplant flesh. Remove from the heat and stir in the crème fraîche.
Season with salt, ground black pepper and thyme.
Cook the lasagne sheets in salt water until al dente. Drain and halve.
Arrange the lasagne sheets, aubergine mixture and the sauce alternately on plates.
Serve garnished with thyme.