Here's Exactly How To Make The Best Brownies Of Your Life

Name: Here's Exactly How To Make The Best Brownies Of Your Life
Cuisine: American
Ingredients: 2½ sticks (1¼ cups) unsalted butter, plus more, softened, for greasing; 8 ounces good-quality semisweet or bittersweet chocolate (60-70% cacao), roughly chopped; ¾ cup unsweetened Dutch process cocoa powder, divided; 1 tablespoon espresso powder; 2 cups granulated sugar; ½ cup dark brown sugar, packed; 2 teaspoons vanilla extract; 2 teaspoons kosher salt; 6 large eggs; 1 cup all-purpose flour; Flaky sea salt, for sprinkling