Set the oven to 200 °C.
Quickly work the pastry ingredients together to make a dough. Leave to rest in the refrigerator for about 30 minutes.
Chop the chocolate and cut up the marshmallows if using the large ones.
Roll the pie dough out on a floured surface, about 4 mm thick. Cut out hearts using a heart-shaped cutter and place on a baking sheet with greaseproof paper. Brush with whisked egg white. Sprinkle a little chocolate and some marshmallows on half of them.
Place the remaining hearts on top and press the edges together using a fork. Press a lollipop stick into each heart and brush with egg white. Sprinkle with cane sugar.
Bake in the lower part of the oven for about 8-10 minutes. Allow to cool.
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