Gooey S'mores Skillet Brownie

Bahan-bahan (12 porsi)

• 1 1/2 sticks (3/4 cup) salted butter
• 1 cup semi-sweet chocolate chips
• 3/4 cups granulated sugar
• 2 teaspoons vanilla extract
• 2 teaspoons instant coffee granules
• 3 large eggs, at room temperature
• 1/3 cup all-purpose flour
• 1/3 cup unsweetened cocoa powder
• 3/4 teaspoon baking powder
• 2 -4 squares graham crackers, broken into pieces
• 1 (4.4 ounce) Hershey chocolate bar, broken into pieces
• 1 cup marshmallow fluff ((or 8-10 marshmallows))