Put 4 1/5 cups (1 L) of the water to boil with the salt.
In a bowl, mix the corn flour with the remaining water. Stir well and add it to the boiling water.
Stir with a wooden spoon until it's thickened and begins to bubble.
Crumble feta cheese in plates. Pour some mixture in, then add more feta cheese and mixture again. Put a lump of butter in the middle and sprinkle with mixed spices.