Add the coconut powder, butter, condensed milk and 8 teaspoons of the pistachio powder to a large nonstick skillet set over medium-low heat and stir until the mixture forms a ball, 7 to 10 minutes. Remove from the heat and let rest until cool enough to handle, about 5 minutes.
Put the remaining 1/4 cup pistachio powder on a small plate. Form the coconut mixture into quarter-size balls. Roll each ball in the pistachio powder to coat.