Preheat oven to 350 degrees. Line a springform pan with parchment paper.
In a mixing bowl, combine the eggs, sugar and vanilla. Add the melted chocolate and melted butter and whisk to combine. Whisk in the flour, salt and instant coffee. Transfer to cake pan and bake for 30 minutes.
In a mixing bowl, add the caramels and heavy cream. Microwave until melted, and stir to combine. Stir in the walnuts. While still hot, pour the caramel sauce and nuts on the cake.