Heat the oven to 200°C/400°F. Heat the olive oil over a medium heat and add the onion, cook for 5 minutes until softened then add the garlic and oregano and cook for another 2 minutes.
Pour in the water and raise the heat slightly, cook until the water has evaporated then add the chopped tomatoes and cherry tomatoes and bring to a simmer, season well with salt and pepper. Cook for 20 minutes.
While the sauce is simmering heat a griddle over a high heat and brush with a little more olive oil. Griddle the aubergine in batches until slightly softened.
When the sauce has finished cooking the cherry tomatoes should have burst and the sauce should have cooked down and thickened slightly.
Start layering your aubergine parmigiana. Grab a baking dish and start with a layer of aubergine slices followed by sauce, repeat the process until you've finished all your ingredients. Top the dish with the mozzarella and big sprinkling of parmesan and panko. Bake for 20-30 minutes until the cheese is browned. Serve with basil leaves.
Nutrition information is an estimate and will vary depending on the exact ingredients used.