Preheat oven to 350 F. Beat butter, sugar and salt until creamy. Slowly add the eggs one at a time. Mix baking powder and flour. Add 1/3 of flour mixture, then 1/3 of milk. Repeat until all is incorporated.
Divide dough into half. To one-half add Grand-Marnier and to the other half add Nutella. Butter and flour a bundt Pan and add the white mixture to the pan. Add Nutella mixture on top of that. Swirl both layers slightly together with a fork to make desired effect.
Bake for about 1 3/4 hours.Let cool slightly in pan for about 5 minutes, remove from pan and let cool completely on baking rack.