In a small bowl, whisk together the spices for the potatoes: onion powder, garlic powder, salt, paprika, chili powder, and cayenne pepper. Set aside.
Wash and place the potatoes in a large stockpot. Cover with water and a generous teaspoon of salt. Bring to a boil and cook for 20 to 30 minutes until fork tender. Drain and pour into a bowl.
Add the oil, cornstarch, and seasoning to the potatoes and toss until coated.
Heat the oven to 400F and line a baking sheet with parchment paper or spray with nonstick spray. Then place the potatoes onto the baking sheet and smash them down with a bowl or glass. Add any remaining seasoning, then roast for 30 minutes until crispy and golden.
While the potatoes bake, melt butter in a skillet then whisk in the flour to begin a roux. Slowly stir in the milk until combined, then season. Add in the vegan cheese and stir until combined. Simmer, stirring often, until desired thickness.
Serve the potatoes topped with vegan cheese sauce, sour cream, and chopped green onion.
Video
Notes
Use red potatoes, baby potatoes, or fingerling potatoes for the best results.
Top with any favorite nacho toppings such as tomato, avocado, olives, etc.