Use the large holes of the grater to grate cheese and potatoes. Transfer the potatoes into a kitchen towel and squeeze as much liquid as you possible can. Place the potatoes into a large bowl. Add cheeses, onion, garlic powder, flour, salt, pepper and eggs. Stir to combine. Heat oil over medium high heat. Use an ice cream scoop to take equal amounts of potato mixture and add to the pan. Use the back of a spoon to flatten the patties. Cook about 3 or 4 patties at a time. Cook until browned about 4 minutes per side. Repeat with remaining potato mixture. Transfer the pancakes to a plate lined with paper towel to remove excess oil. Prepare the dipping sauce by mixing sour cream with chili garlic sauce. Serve the potato pancakes while still warm.