Grate the peeled russets on the large holes of a box grater (or pulse in a food processor). Transfer grated potatoes to a clean kitchen towel and squeeze vigorously to remove as much moisture as possible. Place dried grated potato in a large bowl.

Add the finely grated onion, flour, egg, kosher salt, and black pepper to the bowl with the dried grated potato. Mix until combined; the mixture should hold together when pressed. If too loose, add 1 more tablespoon flour.

Heat a large nonstick or cast-iron skillet over medium-high heat and add 1 tablespoon vegetable oil. When hot and shimmering, scoop 1/3 cup portions of the potato mixture into the pan and flatten into patties about 3–4 inches across and 1/2 inch thick (works for 6–8 small patties or 3–4 larger ones). Do not overcrowd—cook in batches if needed.

Fry for 4–5 minutes on the first side without moving until deeply golden and crisp. Add more oil (about 1 tablespoon) between batches if the pan looks dry. Flip carefully and cook 3–4 minutes on the second side until golden and cooked through. Transfer cooked hash potatoes to a paper towel–lined tray and keep warm in a 200°F (95°C) oven while finishing remaining batches.

Toppings

Cook the bacon: While the last potato batch cooks, crisp the bacon in a skillet over medium heat or on a rimmed baking sheet in a 400°F (200°C) oven for 12–15 minutes until crisp. Drain on paper towels, then roughly chop or crumble.

Shred the smoked cheddar and thinly slice the scallions. Cut the avocado in half, remove the pit, and slice or dice the flesh. Lightly crush the widow chips in a bag or bowl—leave some larger pieces for texture.

Assemble: Place 3–4 warm hash potato cakes on each serving plate (or a pile for a single loaded portion). Immediately sprinkle a generous 1/3–1/2 cup smoked cheddar over the hot potatoes so it melts slightly. Scatter the crumbled bacon and sliced scallions over the cheese. Spoon avocado pieces on top, then sprinkle the crushed widow chips for crunch.

Avocado ranch

Make the dressing: In a small blender or using an immersion blender, combine the 1/2 avocado, buttermilk, mayonnaise, cilantro (or parsley), minced garlic, lemon juice, salt, and pepper. Blend until smooth and creamy. If too thick, add up to 1 tablespoon additional buttermilk to reach a drizzleable consistency. Taste and adjust seasoning.

Finish: Drizzle the avocado ranch over the assembled loaded potatoes. Serve immediately while potatoes are crisp and cheese is warm. Offer extra avocado ranch on the side.