Bread dough: combine warm milk and 4 grams of sugar. Then sprinkle the yeast on top of the liquid and let sit for 5-10 minutes until it gets foamy.

Transfer dough onto a work surface. Add the softened butter and knead until it is fully incorporated. It will be messy at first but as long as we keep kneading, the dough will become less greasy and easier to handle.

Knead for about 10 minutes or until the dough is smooth, elastic, and not tacky.

Coat the dough ball with vegetable oil. Place it in a large bowl and cover with a damp cloth or plastic wrap. Let sit for about 1 hour in a warm area until it doubles in size.

Coffee layer: Dilute instant coffee with hot water. Set aside to cool.

Cream butter until smooth. Add sugar and mix until it is fully incorporated. Mix in the egg, then the coffee solution.

Add sifted flour and mix just until combined. Transfer the batter into a piping bag equipped with a round tip (0.5 cm in diameter).

Assembly: Once the dough is doubled in size, punch out the air. Transfer it onto a work surface and divide into 7 equal pieces. Roughly round up 6 of them and set aside with a cover to prevent drying.

Divide the last piece into 6 equal pieces. Take a piece and flatten it with your palm. Place 1 of the cubed butter filling on the center. Wrap it tight with the dough. Repeat with the rest.

Now flatten one of the big pieces. Onto its center, place the wrapped butter with the seam side down. Wrap it tight, then place on a tray lined with parchment paper. Repeat with the rest.

Cover them and let rise for about 45 minutes until 1.5x bigger in size.

Pipe a layer of coffee batter onto each bun, in a coil-like pattern. Start from the center and leave about 2.5 cm from the bottom.

Bake in a preheated oven at 350°F (180°C) for 18-25 minutes or until the top is crispy to the touch. Best served when still warm.