In a medium bowl, whisk together the all-purpose flour, bread flour, baking soda, baking powder, and salt. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the cold, cubed butter, brown sugar, and granulated sugar on medium speed for 2-3 minutes, until combined and slightly fluffy. Do not over-cream.

Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.

With the mixer on low speed, gradually add the dry ingredients to the wet ingredients. Mix until just combined. Be careful not to overmix. Using a spatula, fold in the chocolate chips and chocolate chunks.

Cover the bowl with plastic wrap and refrigerate for at least 4 hours, or preferably overnight. This step is crucial for thick cookies and deep flavor.

Preheat your oven to 375°F (190°C). Line two baking sheets with parchment paper.

Use a large (3-tablespoon) cookie scoop to portion the cold dough onto the prepared baking sheets, placing them about 3 inches apart. Sprinkle the tops with flaky sea salt.

Bake for 12-15 minutes, or until the edges are golden brown but the centers are still soft and slightly underdone. Let the cookies cool on the baking sheet for 10 minutes before transferring them to a wire rack to cool completely.