Place the almond flour and powdered sugar in a foodprocessor and process until combined and smooth. This can take 1-2 minutes. Process until it comes together in a firm mass.
After a few seconds add in the water, almond extract, and food grade rose water (optional). Process again to combine. The marzipan is well combined if it's slightly sticky.
If the dough is moist and crumbly, process longer. And when the dough is too dry and crumbly, add a little bit of water (like ½ tsp).
Knead the marzipan dough until it gets warm and easily adapts to any form you would like to create (a log, disc or ball) and place it in the fridge, tightly wrapped in cling wrap.