In a medium bowl, stir together the all purpose flour, bread flour, cornstarch, baking soda, salt, and espresso powder. Set aside.
To brown the butter, melt and cook over medium-high heat for 8-10 minutes, stirring occasionally, until brown flecks start to appear all over, and then pour into a bowl to cool.
In a large bowl, beat the cooled browned butter, brown sugar, and sugar until smooth. Beat in the eggs, vanilla extract, and water. Slowly add in the flour mixture until completely combined, and fold in the chocolate chunks, including any smaller flecks.
Scoop the dough into 2 tablespoon-full balls onto a baking sheet. You're going to chill these, so you can put them right next to each other. Sprinkle the coarse salt evenly over the top of all the dough.
Chill for at least 30 minutes, or longer. When you're ready to bake the cookies, preheat your oven to 350 degrees and line two baking sheets with parchment paper or nonstick sheets. Place the pre-scooped cookies about 2 inches apart on the baking sheets, and press down with the bottom of a glass until they are about 1/2 inch thick.
Bake for 10-12 minutes, or until the cookies are golden brown on the edges. Cool on the baking sheets for 5 minutes, and then transfer to a cooling rack. Enjoy!