Eggplant Parmigiana (Parmigiana di Melanzane) | Umami

Ingredients

• 1 ⅘ / 2.6lb large eggplants (aubergines) - about 5 (, sliced lengthways 8mm (1/3")-thick (skin on, Note 1))
• 1/4 cup olive oil ((for brushing))
• 1 2/3 cups parmesan (, finely grated)
• 2 cups basil leaves ((loosely packed), stalks reserved)
• 1 1/2 cups mozzarella (, shredded (for topping) (Note 2))
• 2 tbsp extra virgin olive oil
• 1 onion (, finely diced)
• 5 garlic cloves (, finely minced)
• 600ml / 20oz tomato passata ((Note 3))
• 400g/ 14oz canned tomatoes (, crushed or finely chopped (Note 4))
• 1 1/2 tsp white sugar
• 1 1/2 tbsp fresh oregano (, finely chopped (or 1/2 tsp dried oregano, or 1 sprig fresh basil))
• 1 cup water
• 3/4 tsp salt
• 1/4 tsp black pepper