Preheat your oven to 425°F (220°C). In a saucepan, combine the butter and water, heating until the butter melts and the mixture comes to a boil. Remove from heat and quickly stir in the flour all at once. Keep stirring until the mixture forms a ball and pulls away from the pan.
Let the dough cool for a few minutes. Then beat in the eggs one at a time, mixing well after each addition until the dough is smooth and glossy.
Line a baking tray with parchment paper. Using two spoons, drop long strips of dough (about 3 inches long) onto the tray, leaving space between each.
Bake in the hot oven for 10 minutes. Then reduce the temperature to 375°F (190°C) and bake for another 15 minutes until the eclairs are puffed up and golden brown. Avoid opening the oven door while baking.
Whip the heavy cream until it holds soft peaks.
In a small saucepan, combine the chocolate, butter, water, and confectioners’ sugar. Heat gently, stirring, until smooth and glossy.
When the eclairs are cool, slice them in half lengthwise. Fill each with whipped cream and replace the tops. Dip or spread the chocolate icing over the top of each eclair.
