Line two large baking sheets with parchment paper. Place powdered sugar in a large zip-top bag. Set aside.

Finely chop 1/2 cup pistachios. Roughly chop the remaining 1/2 cup for garnish. In a large heatproof bowl, combine cereal and the 1/2 cup finely chopped pistachios.

In a medium saucepan over low heat, melt white chocolate, pistachio nut butter, and 1/4 cup butter, stirring constantly until smooth. Remove from heat.

Immediately whisk in the dry pudding mix, vanilla, and almond extract until a thick, smooth, green paste forms.

Pour the warm coating over the cereal mixture. Gently fold with a spatula until every piece is evenly coated.

Transfer half the mixture to the bag of powdered sugar. Seal and shake/tumble to coat. Spread on a prepared sheet. Repeat with second half.

While still tacky, sprinkle reserved chopped pistachios over both pans, pressing gently to adhere.

Let cool at room temperature until coating is fully hardened and crisp, 1-2 hours. Store in an airtight container.