Doubling ingredients on panettone cake
I have made larger cakes by doubling the recipe with no problem. Often when changing a recipe, the ratio of dry ingredients to wet can change, but it will remain the same with simple doubling. 

However, do NOT double the cooking time. It's going to cook for longer, but not nearly twice as long. After the regular time, start checking it with a cake tester or toothpick to see if it's completely cooked.