Preheat oven to 375 F. Line a 12 cup muffin tin with paper baking cups.
In a food processor, pulse pistachios until finely ground. In a medium bowl, whisk together pistachios, flour, sugar, baking powder & baking soda. Add peaches, stirring to coat them.
In another bowl, whisk yogurt, butter, eggs, vanilla & orange zest. Fold in the dry ingredients making sure not to over mix.
Divide batter between the 12 muffin cups. Insert 2 or 3 whole raspberries into each muffin. Sprinkle with some slivered pistachios. Push them down a bit into the batter so they don’t fall out when the muffins rise.
Bake for 25 minutes or until risen & golden. Cool in muffin tin for 10 minutes then remove to a wire rack to cool completely. Sprinkle with powdered sugar if you wish.