Making Cranberry Upside Down Cake is straightforward when you follow these steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan.
2. Prepare Cranberries: In a small saucepan, melt 2 tablespoons of butter over medium heat. Stir in the cranberries and ½ cup of brown sugar. Cook until the cranberries begin to soften, about 5 minutes. Pour this mixture into the prepared cake pan.
3. Cream Butter and Sugar: In a large mixing bowl, cream together the remaining ½ cup of butter and ½ cup of granulated sugar until light and fluffy.
4. Add Eggs and Vanilla: Beat in the eggs, one at a time, followed by the vanilla extract. Mix until well combined.
5. Combine Dry Ingredients: In another bowl, whisk together the flour, baking powder, baking soda, and salt.
6. Mix Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Mix until just combined.
7. Add Orange Zest: If using, fold in the orange zest for added flavor.
8. Pour Batter: Carefully pour the batter over the cranberry mixture in the cake pan, spreading it evenly.
9. Bake: Place the cake in the preheated oven and bake for 35-40 minutes or until a toothpick inserted in the center comes out clean.
10. Cool: Remove the cake from the oven and let it cool in the pan for about 10-15 minutes. Then, invert onto a serving plate.

Following these steps will guide you in creating an incredible Cranberry Upside Down Cake that is sure to impress your family and friends.