Follow the instructions on the package to heat one S’mores Flavoured Fondue.
Split the pie dough in half. On a lightly floured surface, roll out each half to make two 20 cm × 23 cm (8” × 9”) rectangles. Slice each piece into six 10 cm × 7.5 cm (4” × 3”) rectangles.
In a bowl, mix the fondue with the butter, marshmallows and walnuts. Let stand for 5 minutes.
In the middle of six rectangles of dough, spoon the fondue mixture, leaving a border. Brush the borders with egg wash. Place the re-maining rectangles on top and seal the edges by crimping with a fork. Brush the dough with egg wash.
Lay the Pop-Tarts on a sheet pan lined with parchment paper. Bake for 15–17 minutes. Remove from the oven and let cool on a wire rack.
Meanwhile, follow the instructions on the package to heat the second S’mores Flavoured Fondue.
When ready to serve, lay the Pop-Tarts on a sheet pan lined with parchment paper and top with marshmallow spread.
Set the oven to “broil” and cook for 1–2 minutes until the spread is golden brown. Remove from the oven.
Drizzle fondue over Pop-Tarts, then sprinkle with graham crackers.