01 - Preheat the oven to 400°F.
02 - Brush the aubergine slices lightly with olive oil. Heat a grill pan or barbecue over high heat. Char the aubergine slices in batches for 2–3 minutes per side until smoky and tender. Set aside.
03 - Heat 1 tbsp olive oil in a saucepan over medium heat. Add onion and cook for 5 minutes until softened. Add garlic and cook for 1 minute. Add tomatoes, oregano, chili flakes, sugar, salt, and pepper. Simmer, uncovered, for 15–20 minutes until thickened. Stir in most of the basil, reserving some for garnish.
04 - Spread a spoonful of tomato sauce on the bottom of a baking dish. Layer with aubergine slices, a little mozzarella, and a sprinkle of Parmesan and Pecorino. Repeat layers until all ingredients are used, finishing with sauce and cheese on top.
05 - Sprinkle breadcrumbs over the top for extra crunch.
06 - Bake for 25–30 minutes until golden and bubbling. Rest for 10 minutes before serving. Garnish with reserved basil.