Preheat oven to 200°C / 400°F (180°C fan-forced).
Toss eggplant and zucchini slices in a bowl with 1 teaspoon of salt. Place them in colander over bowl to sweat and leave to drain for about 10 minutes while you slice the remaining vegetables and prepare the baking dish.
Spread 1 tbsp olive oil, tomato paste and half the garlic over the base of a ceramic baking dish (30cm x 20cm x 5cm / 12" x 8" x 2").
Give the colander a shake to remove excess water off the eggplant and zucchini, then put them back into a bowl. Toss with another ½ teaspoon of salt.
Arrange the vegetables vertically in the dish, alternating eggplant, zucchini, onion and tomato.
Drizzle all-over with remaining olive oil. Sprinkle evenly with remaining garlic, remaining ½ teaspoon of salt, black pepper and Herbes de Provence.
Bake for 40 minutes until the vegetables are soft and lightly browned on the edges.
