Beat egg white and salt until very stiff. Let the sugar trickle in. Mix the almonds, pistachios and flour and carefully fold into the meringue. Pour the macaroon mixture into a piping bag with perforated spout.
Spray small hearts onto a baking tray lined with baking paper. Bake in the preheated oven (electric oven: 150 °C/ gas: level 1) for approx. 15 minutes, allow to cool. Melt the jelly at low heat, let it cool down.
Pour into a freezer bag, cut off a small corner. Spray jelly on the pistachio hearts and let it dry. Makes about 70 pieces.