Milk Chocolate Mocha Blondies

Bahan-bahan (16 porsi)

• 2 cups (250g) all-purpose flour (spooned & leveled)
• 1 teaspoon baking powder
• 1/2 teaspoon salt
• 14 Tablespoons (196g) unsalted butter, melted + slightly cooled (see note)
• 3 or 4 teaspoons espresso powder (see note)
• 1 and 1/2 cups (300g) packed light or dark brown sugar
• 1 large egg + 1 egg yolk, at room temperature
• 1 Tablespoon pure vanilla extract
• 8 ounces (1 heaping cup) milk chocolate (discs, chopped bars, or chips)
• 1/2 teaspoon espresso powder
• 1 Tablespoon warm water
• 3/4 cup (90g) confectioners’ sugar
• 1 Tablespoon milk or heavy cream