Prepare the Bread Dough:
In a mixing bowl, combine the bread flour, sugar, salt, and instant yeast. Gradually add warm milk and mix until a rough dough forms. Knead for about 10 minutes until smooth. Add softened butter and knead until fully incorporated. Cover and let the dough rise in a warm place for 1 hour, or until doubled in size.

Make the Cookie Topping:
In a separate bowl, cream together softened butter and sugar. Add the egg yolk and mix well. Sift in the flour and matcha powder, then mix until a soft dough forms. Add milk if needed to bring the dough together. Wrap in plastic wrap and refrigerate for 30 minutes.

Shape the Melon Pan:
Once the bread dough has risen, divide it into 6 equal portions and shape them into balls. Roll out the cookie dough and cut into 6 circles large enough to cover the bread dough balls. Gently place the cookie dough over each bread dough ball and lightly press to cover.

Create the Signature Melon Pattern:
Use a knife to lightly score a crisscross pattern on top of each bun. Roll each bun in granulated sugar for extra crunch.

Final Proofing:
Place the buns on a baking sheet lined with parchment paper. Cover loosely with a kitchen towel and let them rise for another 30 minutes.

Bake:
Preheat your oven to 350°F (175°C). Bake for 12-15 minutes, or until the cookie topping is slightly golden.

Cool & Serve:
Let the Matcha Melon Pan cool slightly before serving. Enjoy the crisp cookie layer with soft, fluffy bread inside!