Heat oven to 350F (176C). Butter or spray a 2L casserole dish with cooking spray.
For pudding, whisk together sugars, eggs, eggnog, milk, vanilla, zest, cinnamon and salt in a large bowl. Place bread, pecans and cranberries in casserole dish and pour egg mixture over. Soak for 20 minutes.
For topping, combine brown sugar, flour, pecans and salt in a small bowl. Mix in the melted butter until crumbly. Sprinkle over bread mixture and bake until golden and set, about 35 to 45 minutes. Serve drizzled with Vanilla Bean Butter Sauce.