Salted Caramel Brownies

INGREDIENTS

• 3 extra-large eggs
• 2 to 3 teaspoons flaked sea salt, such as Maldon
• 1/2 teaspoon kosher salt
• 8 ounces plus 6 ounces Hershey's semisweet chocolate chips
• 1 tablespoon pure vanilla extract
• 1 cup plus 2 tablespoons sugar
• 5 to 6 ounces good caramel sauce, such as Fran's
• 1 1/2 tablespoons instant coffee granules, such as Nescafe
• 1/2 pound (2 sticks) unsalted butter
• 3 ounces unsweetened chocolate
• 1/2 cup plus 2 tablespoons all-purpose flour, divided
• 1 1/2 teaspoons baking powder