1 - In a medium skillet over medium-low heat, heat 1 tablespoon oil. Add onion, rosemary, and 1/2 teaspoon each salt and pepper and cook until onion is soft and golden, about 7 minutes. Transfer to a large mixing bowl, add potatoes, and mix. Season with salt and pepper.
2 - Spread panko in a shallow dish. In a large skillet over medium-high heat, heat 1 tablespoon oil. Using a 1/3 cup, of potato mixture into 12 cakes. Gently press panko on both sides of each cake. Cook cakes in batches (adding more oil as needed), turning once, until golden brown and heated through, about 8 minutes.
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