Squeeze grated potato to remove most of the liquid. Place in a bowl, add onion, flour salt and pepper. Heat oil and butter in a pan and add about 3 tablespoons of potato. Flaten and cook on both sides until golden and crisp. Drain all cakes on paper towel and keep warm.
Wash spinach several times in cold water. Add olive oil to pan and saute until just wilted. Keep warm.
Add sugar to a saucepan and caramelise over a high heat. Pour the wine carefully into pan. Be careful because this will bubble up. Stir until sugar dissolves and simmer until the sauce reduces by half.
On a warmed plate place a cake in middle, top with spinach, then another cake with more spinach. Place several slices on breast on top and drizzle sauce around plate.