To make the glaze : While the muffins are cooling , prepare the glaze by adding the powdered sugar and lemon juice to a small bowl and whisking until smooth .
When the muffins are completely cool , drizzle a small amount of the glaze over each muffin , sprinkle some chopped pistachios over the top and serve .
Recipe from Chrissie Baker , The Busy Baker
NOTE : These muffins keep well at room temperature in an airtight container for up to 3 days . Freeze in an airtight container or freezer bag for up to 3 months .