A 180°C oven is to be used. Use baking paper that won't stick to a baking sheet. The potato should be cooked for 12 minutes or until soft in a pot of salted boiling water. Return to the pan after draining. One spoonful of milk should be added. Mash with a potato masher until completely smooth. After transferring, let the mixture cool for 5 minutes in a big basin.

Add the spinach, tuna, cheddar, shallot, lemon rind and 1 egg to the potato. Season with salt and pepper and stir to combine.

In a bowl, combine the remaining milk and eggs. Put the breadcrumbs and the flour on different dishes. 2 tablespoons of the potato mixture should be formed into patties. To make 16 patties, repeat with the remaining potato mixture. To coat, dunk one patty in the flour. Clear away any extra flour. To coat, dip in egg mixture and then breadcrumbs. Put the patty on the tray that has been prepared. Repeat with the rest of the breadcrumbs, flour, egg mixture, and patties.

Spray patties with oil. Bake for 20 minutes or until golden. Serve the patties with tomato sauce.