01 - Preheat the oven to 350°F. Line a 12-cup muffin tin with paper liners or grease lightly with nonstick spray.
02 - In a medium bowl, whisk together flour, pistachios, baking powder, baking soda, and salt until well incorporated.
03 - In a large bowl, whisk melted butter and sugar until smooth. Add eggs one at a time, whisking thoroughly after each addition. Stir in yogurt or sour cream, vanilla extract, and almond extract if using.
04 - Gently fold the dry ingredients into the wet ingredients until just combined. Do not overmix—a few small lumps are acceptable.
05 - Divide the batter evenly among the prepared muffin cups, filling each about ⅔ full.
06 - Bake for 18–20 minutes, or until a toothpick inserted into the center comes out clean. Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
07 - Whisk powdered sugar, milk, and vanilla extract in a small bowl until smooth and pourable. Adjust consistency with additional milk if needed.
08 - Drizzle the glaze over cooled muffins. Allow glaze to set before serving. For extra crunch, sprinkle additional chopped pistachios on top while glaze is wet.