Prepare the Pan: Line an 8x8 inch pan with parchment paper, letting the paper overhang the sides. This will make it easier to lift the s'mores out later.
Layer the Graham Crackers: Place the graham crackers along the bottom of the pan, cutting them to fit if necessary.
Melt the Chocolate: Melt 8 oz of chocolate wafers in the microwave, stirring frequently until smooth.
Spread the Chocolate: Spread the melted chocolate evenly over the graham crackers.
Add the Marshmallows: Place the marshmallows on top of the chocolate.
Melt More Chocolate: Melt the remaining 8 oz of chocolate wafers.
Pour and Spread: Pour the melted chocolate over the marshmallows, spreading it evenly.
Top with Graham Crackers: Place the remaining graham crackers on top of the chocolate, pressing down gently.
Freeze: Freeze the s'mores for at least 2 hours, or preferably overnight, until solid.
Cut: Remove the frozen s'mores from the pan using the parchment paper overhang. Cut them into bite-sized pieces.
Freeze Again: Freeze the cut s'mores pieces for at least 2 more hours, or preferably overnight. This is crucial for preventing them from melting too quickly in the hot oil.
Heat the Oil: Heat the oil in a deep fryer to 375°F (190°C).
Prepare the Batter: In a bowl, whisk together the flour, baking powder, salt, sugar, milk, egg, and melted butter until smooth.
Drench in Batter: Bring out a few s'mores chunks at a time. Stick toothpicks into the marshmallows (this will help you handle them). Drench each s'more chunk in the batter, shaking off any excess.
Fry: Carefully lower the battered s'mores into the hot oil. Fry for 1-1.5 minutes per side, or until golden brown.
Drain: Remove the fried s'mores from the oil and place them on a wire rack lined with paper towels to drain.
Serve: Dust the deep-fried s'mores with powdered sugar and serve warm immediately.