Preheat oven to 180 degrees C. Grease baking trays.
In a medium bowl cream together butter and white sugar until smooth. Beat in the eggs one at a time, then stir in the vanilla and ricotta cheese. Combine the flour, bicarb soda, salt and cocoa; gradually stir into the cheese mixture. Drop by rounded teaspoonfuls 5cm apart onto the prepared baking trays.
Bake for 8 to 10 minutes in the preheated oven or until firm. Cool on wire racks.