Add all dry ingredients to a bowl and mix well. Add the milk and pistachio butter to a high speed blender. Blend on high for 30 seconds to mix the pistachio and milk. On low speed add the dry ingredients. Run on high for one minute. On low speed add the cream and egg yolks. Blend on low for 30 seconds to incorporate. Transfer to a pan and slowly heat to 83C/181F. Pour the mix in a zip-lock bag and chill in ice water. Age in fridge overnight. Run in ice cream machine.
Edit. You can also add a little salt to bring out the pistachio flavour even more.