In a bowl, place the 500g of tapioca starch, some thinly grated mozzarella cheese and the egg. Mix it all together very well with your hands.
Add the tablespoon of milk and mix again with your hands, add salt to taste, mix for a bit longer until you end up with a smooth dough that doesn't stick to your hands.
Grease a preheated sandwich maker with margarine or butter, get two pieces of dough and round them into two balls, place them in the sandwich maker, one next to the other, close and toast for 3 minutes. After this indicated time, open the sandwich maker, flip the dough and toast the other side for another minute, if you prefer, leave it for longer to brown to your liking.
You can also add any filling you like, we didn't add any filling here.