1 c. water
Pinch of salt
1/4 c. sugar
6 Tbsp unsalted butter
1 c. flour
Filling, go classic, be creative, your choice
Heat the water, sugar, salt, and butter until the butter is melted and almost boiling. Remove from the heat and add in all of the flour all at once. Dump it all right in. This is my favorite part and one of my favorite things to cook. Keep stirring with a wooden spoon until all of the flour is incorporated. It might take a minute and in the end it should look almost like playdough. Return it to the heat and cook while pushing it around. Keep cooking to remove as much liquid as you can, when it's done it will start to leave a thin film on the bottom of the pan.
Remove from the heat and let it cool somewhat. Line a baking tray with parchment. Then add the pastry to a pastry bag fitted with a large star tip. I like to shape mine in two rows. One pass as long as you want your eclair and then back down the other side, pressing the pastry in to the first layer. If you want small eclairs make them shorter with only one pass.
Bake at 425 until a dark golden brown. Remove from the oven and allow to cool. When they are cool they can be filled, however I like to poke a hole in one side, that will later be used to fill them. I find a chopstick works best, wiggle it around on the inside of the eclair to loosen it.
Use another pastry bag fitted with a long tip to fill them with the custard and then dip the top in melted chocolate. They need to sit with the custard some to soften but not too long or they get too soft.