Make the dough by mixing milk, sugar, yeast, ½ egg, bread flour, and salt. Knead for 10 minutes.
Add 30g unsalted butter and knead for another 10 minutes.
Let the dough rise for 1 hour.
Knead the dough for 1 minute, then let it rest for 15 minutes.
Add 3g salted butter to the dough and let it rise for 35 minutes.
Make the coffee topping by dissolving 3g instant coffee in 5ml hot water, then mixing with ½ egg, 35g powdered sugar, 40g all-purpose flour, and 40g unsalted butter.
Pipe the coffee topping onto the risen dough in a spiral pattern.
Bake at 180°C for 18 minutes.
