Cream
Beat the margarine and sugar in the mixer until obtaining a more or less white cream;
Add the condensed milk and continue beating;
Add the cream and mix well.
Roof
Melt the chocolate bar in the microwave or in a bain-marie until well melted, heat the cream without letting it boil;
Mix the chocolate and margarine and the cream until you get a very homogeneous cream.
Mounting
Line the bottom of the false-bottomed form with the cornstarch cookies, on the sides of the form place the round cookies, always leaving space between one and the other, and add the cream slightly so the cookies don't rise, and then the frosting and that's it;
Serve as you wish.