Preheat oven to 350 F. Grease a 7x11 inch baking dish or spray with cooking spray.
In a large mixing bowl, stir together flour, salt, baking soda, baking powder and sugar.
Whisk together the cocoa powder and the hot coffee until smooth. Let it cool slightly.
Add the cocoa mixture to the bowl with the flour mixture, then stir in the oil, milk, egg and vanilla. Stir until well mixed, then beat until smooth. You can beat by hand or with an electric mixer, but if using a mixer don’t beat too long.
Pour the batter into the pan and bake at 350 for about 25 minutes or until the cake springs back lightly when touched. An 8 inch pan might take a little longer, while a 9 inch square might take a little less. The 25 minutes worked for the 7x11 inch pan.
Let cake cool completely, then making the topping.
Topping: Beat cream until stiff peaks just start to form. Beat in confectioners’ sugar and vanilla. Set aside.
Put boiling water in a large mixing bowl. Add instant coffee and stir until dissolved. Stir in marshmallow crème. Using an electric mixer, beat until smooth.
Fold the sweetened whipped cream into the marshmallow mixture. Spread mixture over cooled cake. Drizzle cake with chocolate syrup and caramel syrup.