Combine the pumpkin seeds and sunflower seeds in the bowl of a food processor with the blade attachment fitted. Pulse until the mixture is crumbly and broken up - don’t run the mixer constantly or you will end up with seed paste! Remove to a bowl and set aside. Repeat with the mushrooms and onions, keeping them separate.

Heat the oil in a large, high-sided frying pan. Add the onions and sauté until softened but not browned, 5-6 minutes. Add the seeds and mushrooms and cook, stirring often for 5 minutes. Add the garlic and cook a further minute.

Pour in the tomatoes, whisk together the vegetable stock and tomato paste and add to the pan, stirring to combine. Pour in the red wine and balsamic vinegar, then bring to a simmer. Stir through the soy sauce, oregano and chilli flakes, season with salt and pepper, then simmer until the liquid has almost entirely evaporated, stirring occasionally.

Meanwhile, heat the oven to 200°C / 400°F / Gas 6.

To make the béchamel, warm the milk in a medium saucepan until hot but not boiling. In a separate saucepan cook the butter and flour together, stirring until the butter is melted and the flour starts to lightly brown. Pour in the hot milk, whisking constantly, then simmer until the mixture is thick. Remove from the heat, stir through the salt and grated cheese then taste and add nutmeg and black pepper.

To assemble the lasagne, spread a layer of the filling onto the bottom of a deep-sided casserole dish. Spoon over some béchamel, spreading it across the filling, then top with lasagne sheets. Repeat the layering, ending with a thick layer of béchamel. Top with sliced tomatoes, drizzle over the olive oil then bake in the preheated oven for 30-40 minutes until puffed, golden brown and beginning to scorch.

Allow to stand for 10 minutes before slicing and serving.