First prepare the caramel. In a large saucepan put the milk carton, cover with water and leave to cook for about 3 hours, until a nice thick caramel, periodically pour more water. While the caramel is prepared to make chocolate mousse. In a large bowl refractory stirring sugar, flour, cocoa and salt. Add 80 ml milk and stir until they combine. Add the egg yolks and stir well. Leaving the bowl aside and prepare the rest of the mousse. In saucepan, pour in the rest of milk (320 ml) and cream. Let the liquid boil. When we see that the milk starts to form foam outta casserole from the fire. Very Carefully transfer the milk mixture into the yolk, stirring constantly. Pour the entire mixture into a clean saucepan and let the fire again stirring constantly, until the mixture does not get the consistency of mayonnaise (about 3 to 5 minutes). Get out of the heat and optional Pour into strainer to give to a smooth mousse texture. Add the grated chocolate and stir the mixture with a spatula. Cover mousse with household foil, allowing him to touch the cream to not form tsipichka. Leave the cream in the refrigerator to cool down and tighten slightly. In bowl, beat cream with sugar additional optional. Peeled and sliced ​​bananas. Smash nice cookies. We make bowls or cups in which to serve trifala. At the bottom of the court, which will serve poured from chocolate mousse, put banana slices, sprinkle well with biscuit crumbs, pour caramel, banana again, again crumbs, cover with cream and decorate optional.