01 - Preheat the oven to 350°F. Line a 12-cup muffin tin with paper liners or grease lightly with butter.
02 - In a medium bowl, whisk together the flour, ground pistachios, baking powder, baking soda, and salt until well blended.
03 - In a large bowl, whisk together the sugar, milk, yogurt, melted butter, eggs, and vanilla extract until smooth and fully incorporated.
04 - Gently fold the dry ingredients into the wet mixture just until combined. Be careful not to overmix as this will result in dense muffins.
05 - Divide the batter evenly among the 12 muffin cups, filling each about three-quarters full. Sprinkle chopped pistachios on top if desired.
06 - Bake for 18–22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
07 - Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.