1. Preheat your oven to 180°C.
2. In a bowl, soak the cashews in 2 cups of warm water for at least 1 hour, or overnight for best results. Drain the cashews before using.
3. Then in a saucepan, heat some oil over medium heat and cook 1 of the diced brown onions until translucent.
4. In a blender or food processor, combine the soaked cashews, cooked onion, 1 tbsp nutritional yeast, dijon mustard, apple cider vinegar, and a pinch of salt. Blend until smooth and creamy. You can add water while you blend to ensure you get a creamy texture but make sure it's not too runny. Set aside.
5. In a large saucepan, heat some oil over medium heat. Add the remaining diced onion and sauté until it becomes translucent.
6. Add the brown lentils, 1 tbsp nutritional yeast, passata, grated carrot, nutmeg, minced garlic, salt, and pepper to the saucepan. Stir well and let it simmer for about 10-15 minutes with a lid on, allowing the flavours to come together. Adjust the seasoning if needed.
7. While the lentil sauce is simmering, prepare the vegetables. Preheat a grill pan over medium-high heat (or alternatively you can use the oven). Lightly brush the zucchini and eggplant slices with olive oil, then grill them in batches until they have grill marks and are slightly softened. Set aside.
8. Take a baking dish (I used one about 30x30x5cm) and spread a thin layer of the lentil sauce at the bottom. Place a layer of lasagne sheets on top, followed by a layer of the bechamel sauce, then grilled zucchini, eggplant slices, and roasted red capsicum. Repeat these layers until you've used all the ingredients, finishing with a layer of lentil sauce on top.
9. Pour the remaining cashew cream mixture evenly over the top layer of lentil sauce, spreading it with a spatula. Cover the baking dish with foil and bake in the preheated oven for 30-35 minutes. Then remove the foil and bake for an additional 10-15 minutes, or until the lasagne sheets are cooked through and the top is golden brown.
10. Once cooked, remove the lasagne from the oven and let it cool for a few minutes before serving. This allows it to set and makes it easier to cut into portions.
Enjoy your delicious vegan cashew lasagne! Serve it with a side salad for a complete meal.