Preheat oven to 350 degrees F
Use a food processor to finely chop the pistachios
Combine flour, baking soda, sugar, and salt
In a separate bowl, whisk together yogurt, milk, eggs, and 4 tablespoons of melted butter
Pour the wet ingredients into the dry ingredients and mix together until just combined
Melt the remaining butter in a large cast iron skillet and mix in the brown sugar
Slice nectarines into thin wedges and arrange the wedges in a single layer on top of the butter and brown sugar mixture
Pour batter evenly over the top of the nectarines and bake for 45-50 minutes or until a skewer comes out clean