1. Batter: beat eggs with sugar for 10 minutes at maximum speed of mixer. Separately, sift flour and baking powder. Turn mixer off, fold in dry ingredients, and mix gently, leaving jimmies to add the last. Bake in a rectangular pan (29 cm x 39 cm) previously greased and lined with butter paper. Preheat oven to 180ºC and bake cake for 20 minutes. Remove from oven and let cool.
2. Filling: in a blender, mix sweetened condensed milk, 1 teacup fresh cream, cocoa, and butter at medium speed for 3 minutes. Put mixture into a large saucepan and set over medium heat, without stopping stirring until mixture detaches from saucepan bottom (about 15 minutes). Remove from heat and let cool. When cold, add the remaining fresh cream beaten to chantilly cream and stir gently until well blended.
3. Assembly: remove butter paper from cake and place it on a clean and dry surface. Then spread half of filling, roll up, and wrap cake with plastic wrap or aluminum foil. Chill for about 1 hour. Remove from refrigerator, take plastic wrap off and spread the remaining chocolate cream all over cake surface. Finalize by sprinkling jimmies on.