Slice the sweet potatoes into thin round slices and par-boil for four minutes
Strain toss with olive oil and a bit of black pepper and set aside
Saute the mushrooms and leeks
Add the rest of the vegetables and simmer to bring out flavour Some people like to roast the butternut squash slightly
In another pot bring veggie broth and soymilk just to a boil Slowly stir in flour and cornstarch reduce heat and continue to whisk until the mixture is thick Add salt and pepper to taste Sometimes I also like to add nutritional yeast
Mix sauce with veggies and pour into pie dish
Cover with sliced sweet potatoes overlapping slightly in a decorative fashion
Cover with tinfoil bake for 40 minutes at 350 degrees
Remove tinfoil bake for 20 more minutes so potatoes will brown