Preheat your oven to 350°F (175°C) and grease a bundt pan with flour.

In a large mixing bowl, whisk together the yellow cake mix and the instant pistachio pudding mix until fully combined.

Add the eggs, milk, and melted butter to the dry mixture and beat with an electric mixer on medium speed for about 2 minutes.

Fold in the chopped pistachios until evenly distributed throughout the batter.

Pour the batter into the prepared bundt pan, smoothing the top.

Bake for 40 to 45 minutes or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for 5 minutes, then invert onto a wire rack to cool completely.

Prepare the icing by whisking together the confectioners' sugar, milk, and vanilla extract until smooth.

Once the cake is cool, pour the icing over the top and garnish with finely chopped pistachios.