Preheat the oven to 425 degrees F, and line 2 baking sheets with parchment.

Place the water, butter, sugar, and salt in a large saucepan.

Cook over medium-high heat, until the butter is completely melted and the mixture is simmering.  

Add in the flour all at once and continue to cook, stirring, for about 5 minutes, or until the dough gathers into a ball and a film begins to form on the bottom of the pot.  

Transfer the mixture to a mixing bowl, and beat on medium speed.  

Drop in the eggs, one at a time. Allow each egg to become fully incorporated before adding the next (about 30 seconds to a minute).

Pipe or spoon the dough onto parchment-lined baking sheets, allowing about 3 inches in between each puff.  

Bake for 25-35 minutes, or until very dry looking, puffed, and deep golden brown.

Place the yolks, sugar, cornstarch, and salt in a medium bowl and whisk to combine.

Heat the milk in a small pot until small bubbles form around the edge, and wisps of steam are rising from the surface.  

Add the hot milk to the egg mixture, a little at a time, whisking to combine.  

When all the milk has been added, transfer the mixture back to the pot and place over medium-low heat.  

Cook the pastry cream, whisking, until thickened.  

Remove from heat and stir in the vanilla.  

Pour the pastry cream through a fine mesh strainer, into a heat-safe bowl.  Use the back of a ladle to press the mixture through the sieve.  

Press a layer of plastic wrap directly onto the surface, and refrigerate until completely cool (about 2 hours)

Whip the cream until it holds stiff peaks.  

Fold the cooled pastry cream into the whipped cream.

Melt the butter in a large skillet, over medium heat.  

Add the apples, sugar, cinnamon, and salt.  

Cook, stirring occasionally, until the apples have softened slightly (about 5 to 10 minutes).

Slice the pate a choux puffs in half horizontally and layer the bottom half with 5 to 8 slices of cooked apples and about 1/4 cup of cream filling.  

Sandwich with the top half of the puff and drizzle with Simply Perfect Salted Caramel Sauce.