Preheat oven to 350F. Grease and flour a 10-inch bundt pan.
Place the softened butter and sugar in the bowl of a stand mixer. Cream them together until they become light and fluffy.
Add the pistachio pudding mix to the butter and sugar.
Mix well, then add one egg at a time, mixing in between each addition.
Add chopped pistachios.
Whisk the dry ingredients (flour, cornstarch, baking powder, salt) together in a medium bowl.
Mix the milk, canola oil, and vanilla together in a large measuring cup.
With the mixer on low, add 1/3 dry mixture to stand mixer, then follow by pouring 1/3 wet mixture. Repeat until you end with the last portion of the wet mixture.
Mix until the ingredients JUST come together. Do not overmix.
Scoop evenly into prepared bundt pan and smooth out the top.
Bake for 45 minutes in a 350F oven. Test with a cake tester and add more time if the tester does not come out dry after inserting it.
FOR THE PISTACHIO GLAZE
Measure the white chocolate chips, heavy cream, and pistachio cream into a large glass measuring cup.
Microwave for 20 seconds, remove and stir. Repeat until almost all of the chocolate has melted, then stir until smooth.
Pour over cake, then decorate. You may need to wait until it sets a bit for larger decorations such as the pistachios/eggs.