Press store bought shells into a 9 inch tart pan. Place a sheet of parchment paper over the top. Add 2 cups of beans. Bake shell for 10 minutes, remove parchment and beans and bake another 5 minutes until set.
Boil sugar and water until it bubbles and changes color. Scald cream in separate pan. Add the hot cream to the hot sugar mixture. Let new mixture boil a few minutes together. Wait until cool. Beat egg and yolk together and add to the cooled cream. Add melted butter and vanilla. Pour walnuts into the tart. Pour mixture over that. Bake tart at 350 degrees F for 40 minutes.
Once cooled boil water and place metal bowl on top (creating a double boiler effect). When boiling turn off heat. Melt chocolate (heat from steam will melt chocolate) and spoon it over tart by drizzling it back and forth.