In a stand mixer bowl, whip the butter then add the sugar and salt. Once you have a paste, add the vanilla extract and the egg then mix again.
Remove bowl from the stand mixer.
Add the almond flour + flour + baking powder. Using the side of a spatula you want to “knife” the mix. Scoop the side and keep cutting through the mix until all the flour is incorporated.
Make a ball, cover, and put in the fridge for 30 mins.
Take it out of the fridge and cut it into 15-20 pieces, shape them as you wish. I find it easier to shape them in my hand, about ½” thick but the result is not as pretty.
Beat the egg yolk with the milk and lightly brush it on the biscuit.
Bake at 350F for about 14 mins
Let cool before you put the icing
When they are cooled, make the icing. In a bowl dump the icing sugar (and lemon juice if you opted for this) + egg white and mix. If it’s very liquid, add more sugar. It should be about toothpaste consistency
If you have an icing bag go for it, it makes a much better result. Let them dry about 60 mins and eat.
To preserve them, put them in a container and cover loosely else they will become “wet”
