Combine sugars, starch, gelatin and salt in med sauce pan.
Add milk gradually while whisking.
Add chocolate.
Cook and whisk over med heat till mixture boils 1 minute, remove from heat.
Place egg yolks in a medium bowl and whisk. Gradually pour 1 cup of hot mixture into egg yolks, whisking constantly.
Whisk egg and chocolate mixture back into remaining chocolate mixture.
Return to medium heat, whisking constantly till mixture boils 1 minute.
Remove from heat and add vanilla.
Stir till cool and thickened slightly.
Pour into pre-baked pie shell and cover pie surface with plastic wrap.
Refrigerate overnight.
Serve topped with sweetened whipped cream.