Cream the butter in a bowl and mix in sugar using a whisk.

Sift cake flour and cocoa powder into the mixture and combine.

Place the dough in a ziplock bag, flatten it, and chill in the freezer for 30 minutes.

In a saucepan, bring milk, water, butter, and salt to a boil.

Remove from heat and quickly mix in sifted flour until combined.

Return the mixture to medium heat and stir until a thin film forms on the bottom of the pan.

Transfer the dough to a bowl and gradually mix in beaten eggs until smooth.

Pipe the choux dough onto a baking tray lined with Teflon sheet.

Spray water evenly and place cookie dough discs on top. Bake at 190°C for 25–30 minutes.

Mix instant coffee with hot water to create coffee concentrate.

Whip heavy cream, coffee concentrate, and condensed milk together using a hand mixer.