Bring the water butter and salt to a slow boil over medium heat.

Add the flour and stir it into the liquid while still over the heat. This will form a dough pretty quickly but continue to cook it for about 3 minutes over medium low flame stirring constantly. If you don’t cook it enough at this stage, then your shells will not puff up enough.

Remove from heat and let the dough cool almost down to room temperature; lukewarm is fine. Stir it every few minutes to help it cool off faster.

Add the eggs one at a time, stirring well until it is completely incorporated and smooth after each egg is added.

Chill the dough in the fridge for a half hour or so. Cold dough works best.

Preheat oven to 375 degrees F.

When chilled, use a piping bag to pipe éclairs about 6 inches long and about 1 ½ inches in diameter on a lightly greased or parchment lined baking sheet. Parchment paper is best because you can actually use a pencil to draw on the 6 inch lines and space them out evenly on the back of a piece the same size as your baking sheet. Just turn the paper over so that you can see the lines through the paper on the opposite side as you pipe out the pastry dough. You should get 10-12 éclairs from this recipe. A heavy plastic Ziploc bag with the corner snipped off will also serve as a piping bag if you don't have one.

Bake in a preheated 375 degree F oven for about 35-45 minutes or longer depending upon your oven. You want to bake these until medium dark brown all over and well dried out in the center. Your éclair shells should not collapse when removed from the oven. Cool completely before filling with chocolate mousse.

Whip your cream to soft peaks and chill in refrigerator.

Melt chocolate with butter on low heat, stirring until smooth.

Cool for 15 minutes.

In double boiler, whisk yolks, sugar and water until pale and fluffy.

Cook and stir over boiling water until mixture reaches 170 degrees F.

Remove from heat and whisk in the chocolate mixture.

Place saucepan in a bowl of ice water and stir constantly until chocolate cools to about room temperature.

Fold in the whipped cream. Chill until quite cold before piping into the cooled choux pastry shells.

Use a spoon handle to poke holes in both ends of the éclair shells and move the handle around gently inside the shell to break up any walls that may have occurred while baking. This will make the shells much easier to fill.

Using a piping bag with a large round or star tip, fill the éclairs with the chocolate mousse, filling half of the éclair from each end.If you like, you can also cut the shells in half horizontally and spoon or pipe in the filling on the bottom half before replacing the tops. Glaze with chocolate ganache.

Melt the chocolate chips and whipping cream together in a double boiler.

You can pipe the ganache topping onto the éclairs or just spread it on with a small spatula. Chill until serving.