Dice butter into 0.5-1 cm / 0.2-0.4 inch. Let it in a fridge until just before you use it. Chop chocolate, set aside.

Sift bread flour, cake flour, and baking powder together and put in a large bowl. Add granulated sugar and salt and stir well with a whisk.

Add the diced butter. Use a scraper to cut butter cubes and mix. Next, use your hands to rub the butter cubes (quickly so that the butter doesn't melt) until the mix looks like fine dry crumbs. Chill in a fridge for 15 minutes.

15 mins later, take the flour-butter mixture out. Add yogurt over some places of the mixture. Use a spatula to fold it until many small lumps form. Add chocolate, and fold roughly. Put it out on the work surface.

Use your hands to gather the dough and press. Fold in half and press, repeat it around five times until the dough almost comes together.

Shape it into a rectangle. Cut it in half, put one on the other, turn around, press it to flatten. Repeat this five times.

Flour the work surface, the dough, and your rolling pin. Roll it out into a circle, 14 cm / 5.5 inches diameter or 1.5 to 2 cm / 0.6 to 0.8 inch thick. Wrap it in cling wrap and let it sit in a freezer for 20 minutes. Preheat an oven to 220℃ / 428 F.

20 minutes later, cut into 6 equal parts. You should flour your knife lightly to cut cleanly. Arrange them on a baking sheet lined with parchment paper not to touch the cut face.

Lower the oven to 200℃/ 392 F and bake for 18 minutes until the edges are golden brown. Freshly baked is fluffy inside, crunchy outside. The next day, it will be more heavy than freshly baked, it tastes good moist, I prefer this one. (Note: Please store them in a closed container to prevent them from drying.)