Boil 6 deciliter of water, salt it, sprinkle the polenta flour and cook for 7-8 minutes constantly stirring.
Take it out of the flame, add butter, a little salt and stir, then pour on some baking paper.
Spread with a wet spatula until it reaches a height of 1 cm. Cut into 16 squares. Let them cool and place them in the plates garnished with caviar.