Stir together flour, sugar and nuts in a large bowl.  Add butter and mix with a pastry blender until butter is the size of small peas. Stir in the egg a little at a time, adding only until dough comes together. Press evenly onto the bottom and sides of a 9" tart pan with a removable bottom and prick all over with a fork. Refrigerate for 1 hour.

Preheat oven to 350F. Bake crust for 25-30 minutes or until golden brown. Remove and let cool. In a medium saucepan over very low heat, melt cream, chocolate and vanilla together. Remove from heat and let cool slightly, then whisk in cheese. Press prunes on the bottom of prepared crust, then spread chocolate filling evenly over the top. Cover and chill for at least 2 hours or until firm. Cut into wedges and top each with a dollop of whipped cream and chocolate shavings, if desired.