Thinly slice the butternut squash as well, stopping when hitting the seeded base (the base will not be used).
In a large pot, simmer the potatoes and squash slices for 10 minutes.
Strain the slices and set aside.
Thinly slice the tomato and the mozzarella.
Prepare a baking pan by covering it with tin foil and greasing the bottom.
For the layering of the stacks, it is imperative to put the butternut squash on the bottom. Also, I like to sprinkle some herbs between 2-3 layers. This is how I layer the stacks: squash, potato, squash, mozzarella, squash, potato, squash, tomato, mozzarella, potato, squash, tomato. You can layer it however best it works for you.
Secure the stacks with toothpicks so they will not slip when in the oven.
Drizzle in olive oil and balsalmic vinegar, and sprinkle with spices.
Bake for at least 30 minutes or until stacks have melded together and the butternut squash is slightly soft to the touch.