To make in a food processor: Add 1 cup of almonds to a food processor with an S blade attachment. Pulse in intervals of 10 seconds 5 times, open the lid and scrape the walls and bottom of the bowl. Put the lid back on.
Continue pulsing for another 20-30 seconds in 10 seconds intervals until fine almond flour forms. Stop as soon as you see fine powder and avoid over processing into almond butter.
To make in a blender: Add 1 cup of almonds to a high speed blender and pulse in 10 seconds increments about 3 times.
Open the lid, scrape the walls and bottom with long wooden spoon and continue pulsing in 10 seconds increments, scraping the walls every 10 seconds. Do so until you see fine powder forming, for another 20 seconds or so.
Almond flour should be stored in a cool dry pantry, fridge or freezer. Light and heat are the enemy of nuts. Unopened bag of almond flour will last 2-4 months in the pantry and 6-12 months in a fridge. Opened bag or homemade almond flour should be stored well sealed or in an airtight container for up to 1 month. After that, refrigerate it.