01 -
Preheat oven to 200°C. Line a baking sheet with parchment paper. In a saucepan, combine water, milk, butter, and salt and bring to a simmer over medium heat.
02 -
Add flour all at once. Stir vigorously with a wooden spoon until a dough forms and pulls away from the sides, about 2 minutes. Remove from heat and let cool for 5 minutes.
03 -
Add eggs one at a time, beating well after each until mixture is smooth, glossy, and thick (it should fall slowly from the spoon). Transfer dough to a piping bag fitted with a large round tip and pipe 8 mounds, about 5 cm wide, onto the baking sheet, well spaced.
04 -
Bake for 20 minutes at 200°C, then reduce oven to 175°C and bake for another 15 minutes, until golden brown and well puffed. Remove and cool completely on a wire rack.
05 -
Place chopped white chocolate in a heatproof bowl. Heat 160 ml cream in a saucepan until just simmering; pour over chocolate. Let stand 2 minutes, then stir until smooth. Stir in vanilla and a pinch of salt. Cover and refrigerate at least 2 hours until well chilled.
06 -
Once cold, add 80 ml remaining cream to the ganache. Whip with an electric mixer until light, fluffy, and soft peaks form.
07 -
Place chopped white chocolate in a small bowl. Heat 120 ml cream in a small saucepan until just simmering; pour over chocolate. Let sit 1 minute, then stir until smooth and glossy. Keep warm until serving.
08 -
Slice the top third off each cooled choux puff. Pipe or spoon whipped ganache generously into the base of each puff. Replace the tops.
09 -
To serve, place each filled puff on a plate. Pour hot white chocolate sauce over the top at the table to create the molten lava effect.