Step 1

Place 2 sticks plus 7 tablespoons unsalted butter in a medium microwave-safe bowl. Place 2 large eggs on the counter. Let both sit at room temperature until the butter is softened.

Step 2

Leaving a few whole, break or chop 10 ounces chocolate feves or discs that are larger than 3/4-inch in half, or coarsely chop 10 ounces chocolate bars.

Step 3

Place 1 3/4 cups bread flour, 1 3/4 cups all-purpose flour, 2 teaspoons kosher salt, 1 1/2 teaspoons baking powder, and 1 teaspoon baking soda in a medium bowl and whisk to combine.

Step 4

Microwave the butter in 10-second increments until about half of it is melted, 10 to 30 seconds total. Transfer to the bowl of a stand mixer (or large bowl if using an electric hand mixer). Add 1 1/2 cups packed light brown sugar and 1 cup plus 1 tablespoon granulated sugar. Beat with the paddle attachment on medium speed for 2 minutes. Increase the speed slightly and beat until light and fluffy in texture, similar to frosting, about 2 minutes. Scrape down the beater and sides of the bowl.

Step 5

Add the eggs and 1 teaspoon vanilla extract. Beat on medium speed until fully incorporated, about 1 minute. Scrape down the beater and sides of the bowl again. Add half of the flour mixture, drape a kitchen towel over the mixer to keep the dry ingredients from flying out, and beat on the lowest speed until mostly combined. Add the remaining flour mixture, cover again, and beat on the lowest speed, then medium speed, until just combined, about 30 seconds total.

Step 6

Add 9 ounces bittersweet chocolate chips (about 1 1/2 cups) and 3/4 cup of the chopped chocolate. Fold in by hand until combined.

Step 7

Line a rimmed baking sheet with parchment paper or a silicone baking mat. Use a 2-inch wide ice cream scoop (about 1/4 cup) to scoop the dough onto the baking sheet, doing your best to scoop so that there are pieces of chocolate at the top of each scoop. The dough balls can be close together on the baking sheet, just not touching. Top the cookies with the remaining chopped chocolate, gently pressing it into the dough.

Step 8

Completely wrap the baking sheet in plastic wrap. Refrigerate for 2 days.

Step 9

Arrange a rack in the middle of the oven and heat the oven to 325°F. Line a baking sheet with parchment paper or a silicone baking mat.

Step 10

Bake the cookies one sheet at a time: Place 6 of the dough balls on the baking sheet, spacing them evenly apart (keep the remaining in the refrigerator). Let the dough sit at room temperature for about 6 minutes.

Step 11

Bake for 6 minutes. Rotate the baking sheet from front to back. Increase the oven temperature to 350°F and bake for 6 minutes.

Step 12

Remove the baking sheet from the oven and give it a careful yet assertive tap against a heatproof surface, then place it on the surface. Working with one cookie at a time, fit a 4-inch round cutter over the cookie. Move the cutter in a circular motion to gently push the edges of the cookie toward the center to shape it into a more uniform round.

Step 13

Return the cookies to the oven and bake until the cookies are set and just barely starting to brown on top, 3 to 4 minutes more at 350ºF. Give the baking sheet another assertive tap or two against the work surface.

Step 14

Garnish the cookies with flaky salt. Let cool on a baking sheet for 5 minutes. Using a flat, wide spatula, transfer the cookies to a wire rack and let cool for at least 5 minutes more before serving. Turn the oven temperature back down to 325ºF before baking each batch and use a cooled baking sheet.