Heat the oven to 200C/fan 180C/gas 6. Put the eggplant slices onto baking paper-lined trays. Roast in the oven for 30 minutes, flipping halfway until softened and crisping at the edges.
Meanwhile, heat a couple of tablespoon of water l in a large pan and cook the onion and garlic for 10 minutes until soft, then add the chopped tomatoes, season with some salt and pepper + the oregano, and simmer for 20 minutes, stirring a few times. Take off the heat.
While the tomatoes are cooking, make the cashew cream:
Soak cashew nuts in hot water for 5 minutes. Then strain them.
Add soaked cashew, dairy-free milk, garlic, nutritional yeast, nutmeg, salt, and pepper to a high-power blender and blend them until smooth & creamy.
When the eggplant, cashew cream, and tomato sauce are ready it's time to assemble.
In a roughly 20cm x 30cm baking dish, layer up some slices of eggplant to cover the bottom of the dish, and add a bit of the tomato sauce. Add another layer of eggplant + tomato sauce, then add half of the cashew cream. Add basil leaves, then repeat with the rest of the ingredients, finishing with cashew cream and basil.
Put the baking dish back in the oven at the same temperature and bake for another 30 minutes.