1. If baking immediately preheat the oven to 415F/204C and line a baking sheet with a Silpat liner or parchment paper.
2. In a medium-sized heavy-bottom saucepan add the butter, salt, granulated sugar, water, and milk. Cook over low-medium until the butter has melted. Let the mixture heat up to just before the boiling point.
3. Add the flour and use a wooden spoon to beat it in, avoiding splashing the liquid, during this, I usually hold the pot off of the heat while mixing the flour in. Once the flour is combined place back on the heat and cook for a couple of minutes, the mixture will come to a ball. If you were to stick a normal spoon into the dough it would stand up straight without falling over, if the spoon falls over the dough has too much moisture still and needs to cook a little longer. 
4. Take off the heat and add to the bowl of an electric stand mixer, or if using a handheld mixer use a large bowl. Let the dough cool for 10 minutes.
5. Once the dough is cooled add three eggs, one at a time, mixing on medium speed after each addition so the egg is fully incorporated. Make sure to use a spatula to scrape the bottom of the bowl as well. The final egg I whisk it in a bowl and add half of it to the dough. You may need the whole egg you may not depending on your batter and the environment you are cooking in. The dough is ready when it is more of a pipe-able texture if you hold the paddle attachment up and let the dough drip off you will notice it falls into a v shape. The dough is easily moveable and elastic but holds its shape, and has a glossy sheen to it. You can also run your finger down the middle of the batter and the indent you make should hold its shape, not caving in on itself.
6. Fit a large piping bag with a large 1/2" round tip or no tip at all for cream puffs or use a 1/2" star tip for eclairs and add the dough. At this point, you can cover the tip with plastic wrap and store this dough in the fridge for up to 5 days or bake it immediately.  
7. When piping for cream puffs or profiteroles I pipe about a 1 1/2 inch circle by piping straight down and letting it expand in both height and width. For eclairs, I pipe about a 3-31/2 inch rectangle. Wet your finger and tap any poking out pastry in, if there are any peaks left out they will burn. Bake for 10 minutes then reduce the temperature to 340F/180C and bake for an additional 18-23 minutes. Do not open the oven door when reducing the temperature. When the choux pastry has baked for 25 minutes total I quickly pull the tray out of the oven and use a sharp knife point or a skewer to prick the shells- this will help release the heat and steam from inside, ensuring the center is dried out. Place the tray back in the oven and cook for an additional 5-10 minutes, you want a gorgeous golden brown color.
8. When the choux pastry is baked let them cool in the oven turned off and door open for 10 minutes then cool completely on the counter in a draft-free place. You don't want to shock the temperature of the pastries and deflate them, before filling.  Store the pastry in an airtight container for up to a day before filling, in my opinion, these taste best the day of. Filled pastries will need to be kept in an air-tight container in the refrigerator.

Chocolate Whipped Cream

1. I like to use a metal mixing bowl you can use your electric stand mixer fitted with the whisk attachment or a large bowl and handheld electric whisk. Place the bowl and whisk in the freezer for at least five minutes to chill before making the whipped cream. This is key! Don't skip it!
2. Once the bowl is chilled add all ingredients, attach the whisk and beat on medium speed for 3-5 minutes, or until you have stiff peaks. This means the cream will hold its texture, it won't puddle down on itself. Place in a  Use immediately or store in an air-tight container for up to 3 days in the refrigerator. Add whipped cream to a large piping bag fitted with a piping tip, I like to use a Wilton 1M tip.

Chocolate Ganache

1. In a glass liquid measuring glass or small/ medium bowl add chopped chocolate and set aside. In a small saucepan add cream and cook until just before the boiling point. Pour directly over chocolate, and let sit for 3 minutes. Add the golden syrup then using a whisk, mix the chocolate and cream until a silky texture. 

Assembly

1. Use a serrated knife to gently cut the choux pastry balls in half and pipe the bottom shell with a thick layer of chocolate whipped cream. Take the top shell and dip it in the chocolate ganache then place it on top of the whipped cream and gently press down to stick to the cream. Enjoy immediately or store in an airtight container in the refrigerator for a day or two.