Preheat the oven to 175° C / 350° F and line a large baking tray with a piece of baking paper.
In a large mixing bowl, mix the almonds, sugar and baking powder.
Place the aquafaba (use only 60 ml / ¼ cup if using amaretto*) and lemon juice in a spotlessly clean bowl – even the tiniest grease residue will inhibit the aquafaba from reaching stiff peaks.
Whip the aquafaba with an electric mixer until stiff peaks form – you need to be able to invert the bowl over your head and the mixture should not move at all.
Gently fold in 2 tbsp of whipped aquafaba into the mixture and then fold the rest in gently.
Add Amaretto (if using), vanilla paste and almond extract. Mix really well.
Form the mixture into balls (I made fifteen 26 g / 0.9 oz balls) and roll them in the icing sugar.
Place the cookies on the prepared baking tray, making sure you leave enough space between them. You can leave them as they are, or gently flatten them a little with your palm. The former look cuter (I think), but the latter get a crispier shell once baked.
Bake for about 17 minutes, until the tops are lightly browned and cracked in places. Allow them to cool completely to crisp up and become less fragile
