Directions:

Chips
Preheat the oven to 375 F. with 2 large baking sheets inside during preheating.
Peel outside skin of the cassavas and then slice thinly approximately 1/16’” with a mandolin or sharp knife (be careful), also be aware sometime cassava can be a little brittle, if some of it falls apart then slice what you can by hand, also the small pieces can still be baked. In a small bowl mix the salt and oil and set aside.
Once sliced, put cassava slices in a large bowl of ice water for 35 to 45 minutes. This eliminates some of the starch. Remove from water and lay on a paper towel to air dry.
Once cassava slices are mostly dry put them in a bowl add the olive oil mixture. Then toss until all the slices are nicely covered with oil. (Pending on cassava you may need to add a little more olive oil.) I like using my hands to make sure both sides of each chip are coated.
Using 2 large preheated baking sheets (two allows for more space to be able to turn easier and for better results), put cassava chips on baking sheets and put them back into the oven. Cook for around 30 to 40 minute but keep a good watch on them and turn them every 10 – 12 minutes. Goal is for them to get nicely toasted and crispy.

Nachos
Preheat oven to 350
Caramelize onions adding salt and Piri Piri. Sauté mushrooms in olive, salt & pepper) till browned, set both aside.
In an oven safe dish start adding ingredients in a layered fashion, add half of the chips, ½ of the cheeses, mushrooms, olives, caramelized onions, second ½ of the chips then again top with cheeses, mushrooms, olives, caramelized onions.
Put into the oven and cook for around 10 to 15 minutes or until all is melted. Take out of the oven and top with avocado, cilantro and green onions and serve.