1. Pour the egg, sugar, salt, vanilla, cornstarch, and flour into the pot. Mix very well. Turn on the heat and mix until melted.
2. Add the milk and mix well.
3. Add the butter and mix again until thick.
4. Carefully place cookies on a baking sheet.
5. Pour the pastry cream on top of the cookies and spread it all over the cookies until completely covered.
6. Repeat until the tray is full. Cover and refrigerate for 1 hour.
7. Melt the chocolate and mix with vegetable oil. Pour on top of the cake and refrigerate for 4 hours.
