Pre-heat your oven to 180C / 356F / gas mark 4.
Drizzle the squash with 1 tablespoon of oil and roast for 20-30 minutes or until soft.
Heat the remaining 1 tablespoon oil in a large, flat bottomed frying pan.
Add the thinly sliced leeks and cook until softened.
Next add the mushrooms and garlic to the pan and cook until the moisture has left the mushrooms and evaporated.
Add the kale and butter beans to the pan and cook until the kale is wilted and the butter beans are hot.
Season with the sage and salt and pepper.
Remove the roast squash from the oven and add to the pan.
In a separate saucepan, melt the vegan butter.
Stir in the flour until you have made a smooth paste.
Slowly add the soy milk, stirring constantly, to make a smooth sauce.
Add 150g of the vegan cheddar cheese along with the nutritional yeast, mustard, onion powder and garlic powder.
Keep stirring the sauce until the cheese has melted and its completely smooth and thick.
Cover the bottom of a large baking dish with half of the mushroom, squash and butter bean mixture.
Pour over one third of the cheese sauce.
Lay over 3 lasagne sheets.
Repeat by layering on the remaining mushroom, squash and butter bean mixture, one third of the cheese sauce and another 3 lasagne sheets.
Top with the remaining cheese sauce and the remaining grated vegan cheddar cheese.
Bake in the oven for 35 - 40 minutes until the cheese is bubbling and the edges of the lasagne are going crispy.