For the cream puffs - In a saucepan heat the water and butter until boiling, add the flour all at once and beat on medium heat for 2 minutes until very stiff. Remove from heat.
Beat in the eggs one at a time until the dough is smooth and continue to beat until it is satinlike.
Line a baking sheet with parchment paper. Drop 8 even mounds of dough onto the parchment paper.
Bake for 35-40 minutes. Remove them from the oven and turn the oven off. Gently slice each puff horizontally slicing about the top 1/3 off so the top will be a bit smaller. Place them back on the baking pan and return to the warm oven for 5 more minutes to dry slightly. Remove and set aside.
Filling
In a small deep bowl beat the egg yolks with the sugar and the pinch of salt until they are pale yellow. Beat in the flour and ½ cup milk.
In a small pot add 1 cup of milk and bring to scalding, or just before it boils and add a little bit of the hot milk to the beaten egg mixture and whisk the egg mixture quickly. Add the egg mixture to the pot with the remaining milk and whisk to mix continuously, cooking until thick. Remove from heat.
Add in the vanilla and butter stirring until the butter is melted. Chill until cool.
Mash the bananas well with a fork and add into the chilled filling. In a medium size bowl whip the cream until firm and fold the banana filling into the whipped cream gently.
Spoon the banana cream into the cream puffs and place the top back on.
Mocha Chocolate Sauce
Add all the ingredients into a microwaveable measuring cup and microwave in 20 second intervals stirring until just melted. Do not overheat.
Drizzle the chocolate sauce over the top of the cream puffs. Enjoy!