Gather and prepare your ingredients. Preheat your oven to 220°C/200°C fan.
Heat the olive oil in a large, oven-proof, shallow pan over medium-high heat. Add the onions and garlic with a sprinkle of salt and pepper and cook, stirring often, for 4-5 minutes, until reduced.
Add the chilli flakes, if using, smoked paprika, and miso, and stir to incorporate.
Add the chestnut mushrooms and cook for 6-7 minutes, until reduced and most of their liquid has evaporated.
Add the beef and cook for 3-4 minutes, just until no longer red. Use your spatula to chop it up as you go. Pour in the tomato passata and water, and bring to a simmer and let it bubble for 4-5 minutes, until reduced. Start with a small amount of water and add more as needed. It should be loose but not watery.
Add the lentils and spinach and cook for 1-2 minutes, until the spinach wilts.
Add the lasagna noodles and cook for 4-5 minutes, until softening but not fully cooked. Stir often to encourage them to stay submerged in liquid.
Place the cheeses and basil in a bowl and stir to combine. Turn off the hob and spoon the cheese over the top of the sauce. There may be some small holes, but they will melt as they bake and cover the surface.
Place into the oven and bake for 12-15 minutes, until golden brown and bubbling. Allow to stand for about 5 minutes before serving.
