Gather your ingredients: almond flour, unshelled roasted pistachios, and powdered sugar. In a food processor, combine these three and pulse until fine without lumps.

Add almond extract and optional rum extract to the processor. Pulse for another 30 seconds until well mixed.

Add the egg white (or vegan substitute) and process for 1 to 2 minutes until a thick dough forms.

If too wet, gradually incorporate more powdered sugar and almond flour, pulsing until firm and not sticky.

Add natural green food coloring and pulse until evenly distributed.

Transfer the marzipan to a dusted surface. Knead for about a minute, shape into a log, wrap in plastic, and refrigerate for at least 30 minutes.

Store tightly wrapped in the fridge for up to a month or freeze for six months. Let come to room temperature before using.