Preheat your oven to 200°C (400°F). In a saucepan, combine water, milk, and butter, bringing it to a boil. Remove from heat and stir in flour until a smooth dough forms. Return to heat, stirring for 2 minutes. Let cool slightly, then beat in eggs one at a time until smooth. Pipe long strips onto a baking sheet and bake for 20-25 minutes until golden. Cool completely.

Whip heavy cream, powdered sugar, and vanilla until stiff peaks form. Transfer to a piping bag and fill each pastry by slicing them in half or using a piping tip.

Heat heavy cream in a saucepan until hot but not boiling. Pour over chopped chocolate and stir until smooth.

Dip the top of each éclair into the chocolate glaze and let it set. Serve immediately or refrigerate.