Low FODMAP Chocolate Chunk Kahlua Buttercream Bars - FODMAP Everyday

Ingredients

• ¾ cup (109 g plus 2 tablespoons) low FODMAP gluten-free all-purpose flour,
• Heaping ½ teaspoon baking powder; (use gluten-free if following a gluten-free diet)
• ¼ teaspoon salt
• ½ cup (113 g; 1 stick) unsalted butter, (melted)
• 1 cup (213 g) firmly packed light brown sugar
• 2 teaspoons instant espresso powder
• 1 teaspoon vanilla extract
• 1 large egg, (at room temperature)
• 6- ounces (170 g) semisweet chocolate chunks ((about ½-inch in size))
• 1 tablespoon Low FODMAP Coffee Liqueur
• 6 tablespoons (85 g; 3/4 stick) unsalted butter, at room temperature,
• 1 ¾ cups (158 g plus 2 tablespoons) confectioners’ sugar
• 1 tablespoon plus 1 teaspoon lactose-free whole milk
• 1 tablespoon plus 2 teaspoons Low FODMAP Coffee Liqueur
• 1 ½ teaspoons instant espresso powder