Melt the butter for the craquelin topping and set aside to cool down. In a small bowl, mix the flour and brown sugar. Pour over the melted butter and stir until combined.

Place the dough between two sheets of baking paper and roll it out thinly. Refrigerate for about 30 minutes to set.

In a medium pot, combine water, butter, and sugar over medium heat until melted.

Remove from heat and add flour all at once, stirring until the batter comes together. Return to low heat and stir for a couple of minutes to dehydrate the mixture until a thin film forms at the bottom.

Transfer to a large bowl and let cool for 10 to 15 minutes until at room temperature.

Beat the eggs in a separate bowl. Gradually add the eggs to the cooled batter, mixing well after each addition until fully incorporated.

Preheat the oven to 180°C (350°F) and grease the bottom of a baking tray.

Place the choux pastry in a piping bag and pipe small mounds on the tray, leaving space between each.

Optionally, cut out pieces of the chilled craquelin topping and place over each choux mound.

Bake for 20 minutes or until puffed and golden. Open the oven door to let steam escape, then bake for an additional 10 to 15 minutes until fully baked.

Transfer choux to a cooling rack to cool completely.

For the chocolate sauce, chop the chocolate and place it in a heatproof bowl. Heat milk until boiling, then pour over the chocolate and stir until melted and glossy.

To assemble, slice each choux in half, add a scoop of vanilla ice cream, and place the lid back on.

Pour chocolate sauce over the profiteroles and serve immediately.