Marshmallow-Surprise Hot Cocoa Cookies

Bahan-bahan (20 porsi)

• 1/2 cup (8 Tbsp; 113g) unsalted butter, softened to room temperature
• 1/2 cup (100g) granulated sugar
• 1/2 cup (100g) packed light or dark brown sugar
• 1 large egg, at room temperature
• 1 teaspoon pure vanilla extract
• 1 and 1/2 cups (188g) all-purpose flour (spooned & leveled)
• 1/3 cup (27g) natural unsweetened cocoa powder
• 1/4 cup (40g) dry hot cocoa mix
• 1 teaspoon baking soda
• 1/8 teaspoon salt
• 2 teaspoons (10ml) milk (any kind, dairy or nondairy, is fine)
• 10 -11 large marshmallows, cut in half
• 8 ounces (226g) semi-sweet chocolate, finely chopped (see Note)