Coarsely chop the pistachios.
Add eggs and erythritol to a bowl and mix with a whisk.
Add almond flour, coconut flour, baking powder, and salt, then mix.
Add melted butter and vanilla extract, then blend evenly.
Add the chopped pistachios and mix thoroughly.
Pour the batter into a pound cake mold.
Bake in a 180℃ oven for 30-35 minutes.
After fully cooling, remove from the mold and slice.