Melt butter and chocolate in the microwave for 20-30 seconds, then let it cool slightly.

Mix egg, sugar, corn syrup, vanilla extract, and salt together.

Add the melted chocolate mixture and mix well.

Sift cake flour, cocoa powder, baking powder, and baking soda into the mixture.

Mix until no dry flour is visible.

Cover the dough with plastic wrap and refrigerate for 1 hour.

Cream butter until soft.

Add sugar and whip until the mixture turns ivory-colored.

Mix in egg, vanilla extract, and salt.

Sift cake flour into the mixture and fold gently until combined.

Place the dough in a ziplock bag and refrigerate for 30 minutes.

Divide the dough into 8g portions and roll into balls.

Divide the chilled chocolate dough into 11g portions and roll into balls.

Flatten the basic dough balls into thin, flat discs.

Wrap the chocolate dough balls with the flattened basic dough.

Place cookies on a baking tray with enough space between them and flatten slightly.

Bake at 160°C for 8-10 minutes.

Let cookies cool on the tray for 3 minutes, then transfer to a wire rack to cool completely.