In a bowl, mix butter and sugar until combined.
Add egg and mix, then add vanilla and mix.
In another bowl, combine flour, salt, baking soda and cocoa powder.
Add dry mixture to wet mixture and mix to combine.
Form into balls and place on a baking sheet.
Bake at 375 degrees for 5 to 7 minutes.
Remove from oven and let cool completely.
In a pan, melt sugar and water until bubbly, then add butter, salt and cream.
Stir together until a caramel forms.
Allow to cool.
Sandwich a dollop of salted caramel between two cookies.