Put hot water, butter, and salt in sauce pan and bring to a boil. Add the flour and stir well until the mixture starts to pull away from the sides of the pan. Using a mixer, then add your eggs one at a time, beating after each egg very well. This step is very important. Drop by teaspoon onto baking sheet and bake for 10 minutes at 425º. Reduce oven temperature to 400º and bake for another 23 minutes. They should be slightly browned and this time could vary so keep checking them. Remove from oven and cool.
Mix all of the remaining ingredients together for the filling. Split the cream puffs when they are cool and fill with the filling mixture. Filling mixture keeps well in the fridge for several days.