Step 1: Prepare the Custard
Dissolve the custard envelopes:
In a glass of cold milk (taken from the total liter), dissolve the custard mixture sachets, stirring well so that there are no lumps.
Heat the rest of the milk:
In a saucepan, heat the remaining milk along with the sugar over medium heat.
Thicken the custard:
When the milk is hot but not boiling, add the dissolved custard mixture and stir constantly with a wooden spoon or whisk. Cook until the mixture thickens.
Cool slightly:
Remove the custard from the heat and let it cool slightly before using.
Step 2: Prepare the Chocolate Covering
Chop the chocolate:
Cut the chocolate bar into small pieces to make it easier to melt.
Melt the chocolate:

Melt the chocolate in a bain-marie or in the microwave in 20-second intervals, stirring between each pause to prevent burning.
Add the cream:
Add the cream to the melted chocolate and mix until you obtain a smooth and uniform cream.
Step 3: Assemble the Cake
Prepare the mold:
Choose a rectangular or removable mold and cover the bottom with baking paper if you wish to make it easier to remove from the mold.
First layer of cookies:
Place a layer of Maria cookies on the base of the mold. If you prefer, lightly dip the cookies in coffee to give them an extra touch of flavor.
Add a layer of custard:
Spread an even layer of custard over the cookies.
Toggle layers:
Repeat the process alternating layers of cookies and custard until the mold is full. The last layer should be cookies to provide a solid base for the chocolate coating.
Step 4: Cover with Chocolate
Add coverage:
Pour the chocolate and cream mixture over the last layer of cookies, spreading it evenly with a spatula.
Decorate:
Sprinkle cocoa powder or add chocolate chips to decorate the surface of the cake.
Step 5: Refrigerate
Rest in the refrigerator:
Place the cake in the refrigerator and let it rest for at least 4 hours. For best results, refrigerate overnight.
Step 6: Serve
Unmold and cut:
Before serving, carefully unmold and cut into individual portions.