01 - Preheat oven to 350°F. Line a standard 12-cup muffin tin with paper baking cups.
02 - Utilizing a food processor, pulse the shelled pistachios until finely ground, taking care to prevent them from forming a paste. Set aside 2 tablespoons of the ground pistachios for later topping.
03 - In a large mixing bowl, thoroughly whisk together the all-purpose flour, finely ground pistachios, granulated sugar, baking powder, baking soda, and salt until uniformly combined.
04 - In a separate bowl, meticulously whisk together the whole milk, plain Greek yogurt, vegetable oil, large eggs, pure vanilla extract, and the optional natural green food coloring until the mixture is smooth and emulsified.
05 - Gently incorporate the prepared wet ingredients into the dry mixture. Stir just until combined, being cautious not to overmix, which can result in tough muffins.
06 - Evenly distribute the muffin batter among the prepared 12 muffin cups. Garnish the top of each with the reserved ground pistachios.
07 - Bake for 18 to 20 minutes, or until a wooden skewer inserted into the center of a muffin comes out clean, indicating thorough cooking.
08 - Allow the muffins to cool within the baking pan for 5 minutes before carefully transferring them to a wire cooling rack to complete the cooling process.