Preheat the oven to 180°C.
Coarsely chop the pistachios.
In a bowl, mix together almond flour, coconut flour, baking powder, and salt.
In a separate bowl, cream unsalted butter with erythritol until smooth.
Add eggs and vanilla extract, and mix well.
Add the dry ingredients and mix, then fold in the chopped pistachios.
Shape the dough into a round disc, flatten it, and cut into triangles.
Place on a parchment-lined baking sheet and sprinkle more pistachios on top.
Bake in the 180°C oven for 20 minutes.