Pistachio Pudding Cake

Flour, for dusting your bundt pan 1 package yellow cake mix 1 package (3.4 ounces) instant pistachio pudding mix4 large eggs1 cup milk½ cup (1 stick) unsalted butter, melted and cooled (plus more for greasing your pan)½ cup chopped pistachios

Icing:2 cups confectioners' sugar2 tablespoons milk2 teaspoons vanilla extract¼ cup finely chopped pistachios