Grease a 9-inch Bundt pan with butter or margarine.
Preheat your oven to 350 F.
Beat the sugar with eggs, adding one egg at a time. Add the butter and using an electric mixer whip for about 3 minutes until light and creamy.
Soak pistachios and hazelnuts in water for a minute or so. This will help prevent them from dropping to the bottom of the cake.
In a separate bowl, mix baking powder with flour and then add the soaked pistachio and hazelnuts. Leave about 2 tablespoons of pistachios for garnish.
Fold the flour mixture into the egg and butter mixture slowly, and mix until fully incorporated.
Pour the batter into the Bundt pan and bake for about 40 minutes. Allow the cake to cool before glazing.
In a small bowl, mix Jello pistachio instant pudding with 1 cup of milk and whisk to combine. Once the mixture is set, glaze the top of the Bundt cake and garnish with the remaining pistachios.