Prepare the mini pie crusts according to the package directions. Let them cool completely.
In a medium saucepan, whisk the sugar and egg together over low heat. Whisk until the mixture reaches 160 degrees on a thermometer (about 10 min).
Remove from the heat and whisk in the melted chocolate, vanilla, and salt. Keep whisking until smooth.
Set aside to cool to room temperature.
In another bowl, beat the butter until fluffy. Add in the chocolate mixture and beat until butter is full combined. Fold in the whipped topping. Do not over mix.
Using a piping bag with the tip cut off OR simply using a spoon, add the filling into each pie crust. *Note, you will most likely have extra filling, especially if you don’t heavily fill each crust.
Top each pie with whipped cream and chocolate pieces/shavings.