Make the croissant dough

• Mix the flours, sugar, crumbled yeast, salt, cold water and cold milk into a smooth dough.
• Knead until the dough is elastic and smooth.
• Flatten into a rectangle, wrap and chill.

Prepare the butter block

• Pound the cold butter between sheets into a flat rectangle.
• Chill until firm.

Laminate the dough

• Enclose the butter block in the dough.
• Roll out and fold the dough in three, then chill.
• Repeat the rolling and folding, chilling between each fold.

Bake the brownie layer

• Melt the dark chocolate with the butter.
• Whisk in the eggs and brown sugar, then fold in the flour and cocoa powder.
• Spread in a lined tray and bake at 180 °C, then cool completely.

Shape the croissants

• Roll the laminated dough into a long thin rectangle.
• Cut into triangles.
• Spread Biscoff spread and add a piece of brownie, then roll each triangle into a croissant.

Proof and bake

• Place the croissants on a tray and proof until puffy.
• Brush with beaten egg.
• Bake at 190 °C until deep golden.