01 - Preheat your waffle iron to medium-high heat setting to ensure proper crisping.
02 - Grate the peeled russet potatoes using a box grater. Transfer the grated potatoes to a clean kitchen towel and firmly squeeze out excess moisture until potatoes feel relatively dry to the touch.
03 - In a large mixing bowl, combine the dried grated potatoes, finely grated yellow onion, large egg, all-purpose flour, garlic powder, salt, and black pepper. Mix thoroughly until all ingredients are evenly distributed and the mixture holds together when pressed.
04 - Pour the melted unsalted butter into the potato mixture and stir until completely incorporated throughout the batter.
05 - Lightly grease both top and bottom plates of the preheated waffle iron with vegetable oil or nonstick cooking spray to prevent sticking.
06 - Spread an even, generous layer of the potato mixture onto the bottom waffle iron plate, being careful not to overfill. Close the lid and cook for 10-12 minutes until deeply golden brown and crispy throughout.
07 - Using a heat-resistant spatula, carefully lift and remove the cooked hashbrowns from the waffle iron. Repeat the cooking process with the remaining potato mixture until all batter has been used.
08 - Serve the crispy waffle iron hashbrowns immediately while hot and crispy. Optionally garnish with fresh chopped herbs such as chives or parsley, and offer condiments like sour cream, ketchup, or hot sauce on the side.