Chocolate chunk butterscotch cookies

Adapted from Flour bakery cookbook

MAKES ABOUT 24 COOKIES
1 cup (2 sticks/228 grams) unsalted butter, at room temperature
¾ cup (150 grams) granulated sugar
¾ cup (165 grams) firmly packed light brown sugar
2 eggs
½ teaspoon vanilla extract
1 cup (140 grams) unbleached all-purpose flour
1 cup (150 grams) bread flour
1 teaspoon baking soda
½ teaspoon kosher salt
9 ounces (255 grams) semisweet chocolate, chopped (about 1½ cups)
2½ ounces (70 grams) butterscotch chip (about ½ cup)

• Using a stand mixer fitted with the paddle attachment (or a handheld mixer or a wooden spoon), cream together the butter, granulated sugar, and brown sugar on medium speed for about 5 minutes, or until the mixture is light and fluffy. (This step will take 10 minutes if using a handheld mixer or a spoon.) Stop the mixer a few times and use a rubber spatula to scrape the sides and bottom of the bowl and the paddle to release any clinging butter or sugar. Beat in the eggs and vanilla on medium speed for 2 to 3 minutes, or until thoroughly combined. Scrape the bowl and the paddle again to make sure the eggs are thoroughly incorporated. 
• In a medium bowl, stir together the all-purpose flour, bread flour, baking soda, and salt until well mixed. Add the semisweet chocolate and butterscotch chip, toss to combine. On low speed (or with the wooden spoon), slowly add the flour-chocolate mixture to the butter-sugar mixture and then mix just until the flour mixture is totally incorporated and the dough is evenly mixed.
• For the best results, scrape the dough into an airtight container and let it rest in the refrigerator overnight (or for at least 3 to 4 hours) before baking. When you are ready to bake, position a rack in the center of the oven, and heat the oven to 350 degrees F. 
• Drop the dough in ¼-cup balls onto a baking sheet, spacing them about 2 inches apart. Flatten each ball slightly with the palm of your hand. 

• Bake for 12 minutes, or until the cookies are golden brown on the edges and slightly soft in the center. Don’t let them get brown through and through. Part of their appeal is the chewiness of the slightly under baked centers. Let cool on the baking sheet on a wire rack for 5 to 10 minutes, then transfer the cookies to the rack to cool completely. 
• The cookies can be stored in an airtight container at room temperature for up to 3 days. The unbaked dough can be stored in an airtight container in the refrigerator for up to 1 week.