Preheat oven to 400 degrees F.
Bring the water to a boil in a medium-sized, sauce pan. Add salt and butter and stir until the butter has melted. Reduce the heat. Add the flour and beat the mixture until it comes away from the sides of the pan and forms a smooth ball in the center.
Remove from heat and add eggs, one at a time, beating well. Using a dessert spoon, shape the puffs and place them on a lightly greased cookie sheet.
Bake at 400 degrees F for 8 minutes, then reduce heat to 350 degrees F and bake for an additional 10-12 minutes.
Remove puffs from the oven and let cool. Slice off the top of each puff and fill the cavity with cream.
Arrange puffs in the shape of a pyramid. Pour Coffee Rum Sauce over them and serve.
Slowly add the cold coffee to the whipped cream, and fold in well. Sweeten to taste.
Coffee Rum Sauce:
Slowly melt sugar in a saucepan over low heat, stirring constantly. Gradually add strong coffee, continuing to stir constantly until the sugar is completely dissolved. In a small bowl stir the cornstarch into the cold coffee and combine with heated mixture. Cook combined ingredients until they boil and thicken. Remove from heat. Add butter and rum. Stir until butter melts. Let cool to room temperature.