Triple Chocolate Espresso Cookies

INGREDIENTS

• 1 tablespoon dark rum (optional)
• 1 teaspoon pure vanilla extract
• 2/3 cups granulated sugar
• 1/4 teaspoon baking powder
• 2 large eggs, at room temperature
• 1/2 cup dark brown sugar, tightly packed
• 1/2 teaspoon baking soda
• 1/2 cup (1 stick) unsalted butter
• 1/4 teaspoon kosher or sea salt
• 1 1/2 cup unbleached all purpose flour
• 1/2 cup natural (non-alkalized) cocoa powder
• 12 ounces semi-sweet chocolate chunks or chips, divided
• 1 tablespoon (or less, to taste) instant espresso powder (recommended: Medaglia d'Oro)