Drop raw almonds into the boiling water and cook for 30 seconds.
Remove almonds from the hot water and place them in a colander.
Rinse almonds under cold running water until cooled.
Using your fingers pinch off outer skins. Skins should come off quite easily.
Spread almonds out in a single layer on a large cooking sheet and allow them to dry overnight.
Once almonds are completely dry place a handful in a blender and pulse the blanched and dried almonds into a powder. Do small pulses to avoid the nuts from getting warm and releasing their oils. You want a poster not a nut butter.
Dump ground almonds into a sieve and sift into a bowl until you're left with just the larger pieces in the sieve.
Return larger almond pieces back to the blender and repeat the process, pulsing just a few times and then sifting. Repeat this process until all the nuts are finely ground into a powder.
Store almond flour in an airtight container a cool dark location or in the fridge for up to 2-3 months. Freeze for longer storage.
Notes
Be sure the almonds are completely dry before grinding them. Try not to overprocess them or they will turn into almond butter if ground too long.