Make the Truffle Filling:
In a heatproof bowl, combine the pistachio butter and 4 oz of white chocolate.
Place the bowl over a pot of simmering water, stirring occasionally, until the chocolate is fully melted and combined with the pistachio butter.
Remove from heat and refrigerate the mixture for 45 minutes to 1 hour, allowing the truffle filling to harden but still remain workable.
Form the Truffles:
Once the filling has firmed, use a small ice cream scoop or spoon to portion the filling into 13 equal pieces.
Place the truffle portions onto a parchment-lined baking sheet, then refrigerate for another hour to firm them further.
Coat the Truffles:
Melt the remaining 6 oz of white chocolate in a heatproof bowl over simmering water, stirring until smooth.
To coat, dip the bottom of a truffle into the melted chocolate, place the truffle on a fork, and use a spoon to drizzle chocolate over the top to cover it completely.
Let the excess chocolate drip off before returning the truffle to the parchment-lined baking sheet.
Immediately sprinkle some ground pistachio over the top of each truffle before the chocolate hardens.
Chill and Serve:
Once all the truffles are coated and garnished, place the baking sheet back in the refrigerator for 30 minutes to 1 hour to let the chocolate set completely.
Serve chilled or at room temperature and enjoy these delicious pistachio truffles!