In a medium skillet, over med-low heat, heat 1 T. oil.
Add onion, rosemary, and 1/2 t. each of salt and pepper. Cook until onion is soft and golden, about 7 minutes.
Transfer onion mixture to a large mixing bowl. Add potatoes and mix. Season with salt and pepper.
Spread panko in a shallow dish. In a large skillet over med-high heat, heat 1 T. oil.
Using a 1/3 cup measure, form 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.
Go to full version of