Preheat oven to 325°F (163°C).

Melt 2 cups of the semi-sweet chocolate chips in the microwave in 30-second intervals, stirring after each interval until just melted. Set aside.

Sift together the all-purpose flour, bread flour, cocoa powder, baking powder, and salt in a medium bowl. Set aside.

In a large bowl, beat the softened butter, granulated sugar, and light brown sugar together until creamy. Add the melted chocolate and mix until combined.

Add the eggs, one at a time, and the vanilla extract to the butter mixture, mixing well after each addition.

Gradually add the dry ingredients to the wet ingredients, mixing by hand until fully combined.

Fold in the remaining 2 cups of semi-sweet chocolate chips.

Line cookie sheets with parchment paper or grease-proof paper. Drop the dough onto the prepared baking sheets, 2 inches apart, using a tablespoon.

Bake for 12 to 14 minutes or until the tops of the cookies have cracked.

Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.