To make sponge, put milk, yeast, egg and 1 cup of flour in a heavy duty mixer.

Mix the ingredient with rubber spatula just until everything is blended

Spinkle over the remaining 1 cup of flour to cover the sponge. Set the sponge aside to rest uncovered forc30-40 minutes

After resting time, add sugar, salt, 4 eggs and 1 cup of flour to the sponge

Set the mixer, mix in low speed until everything comes together

Spinkle another 1/2 cup of flour. Scrape down the side of the bowl and increase mixer to medium speed. Beat for about 15 minutes

Add room temperature butter portionwise (1 tbsp each time) into the dough. Beat until butter is incorporated

Transfer the dough to large buttered bowl. cover with plastic wrap. Proof for 2 hr until doubled in size.

Deflate the dough. Do the second proof by covering again with plastic wrap and keep in the fridge for at least 4-6 hours.

Take tue dough out from fridge. Flat the dough to 1/4 inch thick. Then apply chocolate ganache (or Nutella) all over the dough

Roll the dough in a log shape. and cut to 3 inch long. Put the dough in baking cup.

Cover and raise the dough for 1 h. Then apply egg wash and bake at 180C for 20 minutes.