Boil potatoes in salted water in a large pot for 15-17 minutes or until tender, but not too soft. Drain and set aside.
Line a baking sheet with parchment paper and grease with 1 tablespoon olive oil.
Preheat oven to 425 degrees F.
Arrange potatoes onto prepared baking sheet. Using a potato masher, fork, or bottom of heavy glass to smash potatoes until they begin to split and flatten but remain whole.
Brush smashed potatoes with 1 tablespoon olive oil.
Season potatoes with salt, garlic powder, onion powder, and ground pepper.
Bake for 25 minutes or until golden brown.
Brush with remaining 1 tablespoon of olive oil, then top with shredded cheeses.
Bake for an additional 5-6 minutes or until cheese is just beginning to bubble.
Top with chopped parsley and serve with sour cream if desired.