01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners.
02 - Using a food processor, pulse pistachios until finely ground but not pasty. Reserve 2 tablespoons for topping.
03 - In a large mixing bowl, whisk together flour, ground pistachios, sugar, baking powder, baking soda, and salt until evenly distributed.
04 - In a separate bowl, whisk together milk, Greek yogurt, vegetable oil, eggs, vanilla extract, and food coloring if using until smooth and combined.
05 - Pour wet ingredients into dry ingredients and fold together gently using a spatula just until combined. Do not overmix.
06 - Divide batter evenly among muffin cups using a scoop or spoon. Top each muffin with reserved pistachio pieces.
07 - Bake for 18-20 minutes until a toothpick inserted into the center comes out clean and tops are golden.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.