Place a rack in middle of oven; preheat to 350°. Whisk 1¾ cups (219 g) all-purpose flour, 2¼ tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, ¾ tsp. baking soda, and ¼ tsp. baking powder in a small bowl to combine; set dry ingredients aside.

Cook 14 Tbsp. (1¾ sticks) unsalted butter in a large saucepan over medium heat, swirling often and scraping bottom of pan with a heatproof rubber spatula, until butter foams, then turns dark brown, 6–8 minutes. Add remaining ¼ cup (31 g) all-purpose flour (butter will foam immediately, but don’t worry; just keep stirring) and cook, stirring constantly, until mixture is deep golden brown (the shade of a chai latte), about 2 minutes. Scrape butter mixture, including any browned bits at the bottom of pan, into a medium heatproof mixing bowl.

Add 1¼ cups (packed; 250 g) dark brown sugar to butter mixture and whisk until no large lumps remain. Add 1 large egg, 1 large egg yolk, and 2 tsp. vanilla bean paste or vanilla extract and whisk vigorously until sugar is dissolved and mixture is smooth and paler in color, about 1 minute. Using a rubber spatula, add reserved dry ingredients and fold in until no dry spots remain (dough will be thick and maybe even a touch greasy). Cover and let rest at room temperature 10–20 minutes (this ensures thicker cookies).

If making medium cookies, using a #16 cookie scoop (about ¼ cup), portion out 12 balls of dough (about 56 g each).

If making large cookies, using a #10 cookie scoop (about 6 heaping Tbsp.), portion out 8 balls of dough (about 85 g each).

Divide dough balls between 2 parchment-paper-lined baking sheets. Working in 2 batches, bake cookies until firm and golden brown around the edges, 9–11 minutes for medium, 10–12 minutes for large. Let cookies cool on baking sheets. Do Ahead: Cookies can be baked 3 days ahead. Store airtight at room temperature.