Add the sweetened condensed milk, egg yolks, cornstarch, salt, and one cup of whole milk to a medium saucepan. Whisk until smooth.
Add the remaining three cups of milk and whisk again.
Place the saucepan over medium heat. Cook, whisking often, until thickened and gently bubbling. Continue cooking for two to three minutes.
Remove from the heat. Stir in the butter and vanilla extract until smooth.
Transfer the vanilla cream to a bowl. Press plastic wrap directly onto the surface and let it cool slightly.
In a second saucepan, whisk together the sugar, cocoa powder, cornstarch, and salt.
Slowly whisk in the milk. Cook over medium heat until thickened and gently bubbling. Continue cooking for two minutes.
Remove from the heat. Stir in the chocolate chips, butter, and vanilla extract until smooth.
Stir together one cup of milk and one teaspoon of vanilla extract in a shallow bowl.
Spread a thin layer of vanilla cream in the bottom of a 9×13-inch dish.
Quickly dip cookies into the milk mixture and arrange them in a single layer over the cream.
Spread half of the remaining vanilla cream over the cookies.
Sprinkle chopped bonbons over the vanilla cream.
Add another layer of dipped cookies.
Spread the chocolate cream over the cookies.
Sprinkle more chopped bonbons over the chocolate cream.
Add one more layer of dipped cookies.
Spread the remaining vanilla cream over the top.
Cover and refrigerate for at least four hours, or overnight for best results.
Beat the heavy whipping cream, powdered sugar, and vanilla extract until stiff peaks form.
Spread the whipped cream over the chilled pavé.
Top with chocolate shavings and extra chopped bonbons.
Chill for 30 more minutes before serving, if time allows.