Prepare an 8 or 9 inch pie shell. Blind bake to fully done. Cool.

1. Melt the chocolate in a small bowl over a double boiler to just melted.  Remove to the counter to rest.  Alternatively, you may use the microwave, 5-10 seconds at a time. 
   

2. Create a double boiler with a medium pot filled with 2 inches of water and a metal bowl which fits nicely on top.  Turn the burner to medium high.  Place the eggs and the 1/2 C of sugar and coffee into the bowl and whisk to combine.
   

3. When the water is steaming, place the bowl over the top of the pot.  The water should not touch the bottom of the bowl.  Whisk the egg mixture over the steam, making sure to incorporate all the eggs from the sides of the bowl.  Whisk at a brisk pace until the eggs start to thicken. 
   

   When you remove the whisk and see the egg mixture sitting a bit on top of itself and leave a trail in the eggs in the bowl, then you are done.  Remove from the heat, whisking for a minute afterward to prevent the eggs from coagulating on the sides of the bowl.
   

4. While the egg mixture cools, paddle the butter and sugar and salt until fluffy and pale.  Add the melted cooled chocolate and paddle to mix.  Add the egg mixture and paddle again to thick and fluffy.
   

5. Add the filling mixture to the prepared pie shell.  Spread the filling evenly along the bottom to the edges of the crust. Cover the filling with plastic and chill while making the whipped cream topping.
   

6. Whip the heavy cream on medium speed with the stand mixer or by hand.  When the cream starts to gain volume, add the sugar and finish whipping slowly and steadily until fully whipped. 
   

   Spread on top of the chocolate filling, mounding the cream in the center and smoothing toward the pie shell.  Top with grated chocolate bits or chocolate jimmies.
   

7. Allow the pie to chill several hours before slicing.  You may wait to top just before service.  The important part is letting the filling set up.