Place the potatoes in a large pot and cover with cold water.
Bring to a boil, reduce the heat, and cook for 12 to 15 minutes, until fork-tender.
Drain the potatoes thoroughly and let them sit for a few minutes to release excess steam.
Transfer the potatoes to a large bowl and mash until mostly smooth.
Let the potatoes cool for approximately 10 minutes.
Add the cheddar, mozzarella, green onions, parsley, garlic powder, salt, and black pepper.
Stir in the beaten egg and ½ cup of breadcrumbs.
Refrigerate the mixture for 20 minutes if it feels soft.
Preheat the oven to 425°F and line a baking sheet with parchment paper.
Place the remaining breadcrumbs in a shallow bowl.
Scoop approximately 1½ tablespoons of potato mixture and roll it into a ball.
Coat each bite lightly with breadcrumbs and arrange it on the prepared baking sheet.
Lightly brush or spray the bites with olive oil.
Bake for 18 to 22 minutes, turning halfway through, until golden and crisp.
Rest for 3 to 5 minutes before serving with your favorite dipping sauce.
