Grease your 9-inch bundt pan with butter or margarine. Preheat that oven to 350°F.
In a mixing bowl, beat the sugar with eggs, one at a time. Add the butter and whip it all together using an electric mixer for about 3 minutes until it’s light and fluffy.
In another bowl, mix your flour and baking powder. Then give those pistachios and hazelnuts a quick soak in water, just for a minute. Drain them, toss them into the flour mixture (leave out about 2 tablespoons of pistachios for that final flourish), and stir. This helps keep them from all sinking to the bottom like sunken treasure.
Gently fold the flour/nut mix into your wet ingredients. Don’t rush it, be slow and careful. Once it’s all mixed in, pour the batter into your prepared bundt pan.
Slide it into the oven and bake for around 40 minutes.
Once it’s baked, let it cool completely before doing anything else.
In a small bowl, whisk your pistachio pudding mix with 1½ cups of milk until it sets up nice and creamy and like soft frosting. Then spoon (or slather) it over your cooled cake and sprinkle the rest of the pistachios on top.
