Move oven rack to lowest position to prevent the top of your bread from burning before the rest of it has finished baking. Preheat oven to 350 ° Fahrenheit (176 ° Celsius).
In a large bowl, combine the wet ingredients: milk, oil, vanilla, and eggs.
In another bowl, mix the dry ingredients together: flour, sugar, salt, baking soda, and baking powder.
Mix the wet and dry ingredients. Then, stir in the cranberries and zest.
Pour the batter into your lightly greased 9" by 5" baking pan.
Cook for about 1 hour and 10 minutes (or adjust according to your pan size). If an inserted toothpick comes out clean, it's done.
Let your bread cool for 10 minutes before removing the bread from the pans. Allow the bread to cool completely (about 2 hours) on a wire rack before you cut and serve your bread.
Pipe buttercream icing over your bread after it has cooled.