Basically summer vegetables roasted in olive oil, with salt, pepper and lots of garlic. Here in the Catalan part of France it is considered to be a local speciality, so all the recipes, inevitably passed down from grandma, are excessively complicated. They needn't be.
Here's how to do it. Forget the aubergines/eggplant, uuggh ! Slice zucchini/courgettes thinly, add peppers sliced in to 4 or 5 pieces, tomatoes and onions sliced to 0,5cm, minimum 10 cloves of garlic, salt (fine), pepper, olive oil. Into the oven at 200°C for 60 minutes. Cool, serve with basilic and large salt. Often served cold, sometimes with sherry vinegar.
It looks so delicious! I was born and raised in the south of France and I remember such dishes including the awesome pottery dish you prepared your Escalivade:-)