Remove the ribs and seeds from the red pepper and chop it finely. Peel and thinly slice the onions.
Sauté these vegetables in a frying pan with 2 tablespoons of olive oil over medium heat. Remove from heat once the onions turn translucent.
Slice the zucchini and eggplant thinly, then brown them quickly in 2 tablespoons of very hot olive oil in a pan over high heat.
Slice the tomatoes and remove the seeds.
Preheat the oven to 210°C (th. 7).
Roll out the puff pastry and line a high-edged pie dish with a removable bottom for easy unmolding.
Layer the vegetables in the dish. Between each layer, season with salt and pepper, sprinkle with grated Parmesan, and scatter chopped basil. Finish with alternating slices of tomatoes, zucchini, and eggplant on top.
Sprinkle the remaining Parmesan over the top and drizzle with the remaining olive oil. Bake for 40-45 minutes until golden.
Unmold and serve hot. This Provençal classic highlights fresh seasonal vegetables in a flavorful, layered gratin.
