Mix softened butter with sugar until well combined.

Sift cake flour and fold it into the butter mixture gently.

Roll the dough to 2-3mm thickness and freeze for at least 1 hour.

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

Turn off the heat and quickly mix in sifted all-purpose flour.

Turn the heat back on and cook until the mixture forms a smooth ball.

Transfer the dough to a bowl and let it cool slightly before adding vanilla extract.

Gradually add beaten eggs in portions, mixing thoroughly each time.

Pipe choux dough into 5cm diameter circles on a baking sheet.

Cut frozen biscuit dough into 5cm circles and place on top of choux dough.

Bake at 190°C for 15 minutes, then reduce to 160°C and bake for another 15-18 minutes.

Transfer baked choux to a cooling rack and let them cool completely.

Mix custard cream mix with milk and heavy cream until smooth.

Create a hole at the bottom of each choux and pipe in the filling generously.