Creating a Nectarine Upside Down Cake is simple when you follow these easy steps:

1. Preheat the Oven: Set your oven to 350°F (175°C) and grease a 9-inch round cake pan.
2. Prepare the Topping: In a saucepan, melt the butter over medium heat. Add the brown sugar and stir until dissolved. Remove from heat.
3. Arrange Nectarines: Pour the butter and sugar mixture into the prepared cake pan. Arrange the sliced nectarines on top in a circular pattern.
4. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, and salt.
5. Combine Wet Ingredients: In a large bowl, cream together the granulated sugar and remaining butter. Add the eggs, milk, and vanilla extract, mixing until combined.
6. Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
7. Pour Batter: Carefully pour the batter over the arranged nectarines in the cake pan.
8. Bake: Place the cake in the preheated oven and bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
9. Cool: Once baked, remove the cake from the oven and allow it to cool in the pan for 15-20 minutes.
10. Invert the Cake: Carefully run a knife around the edges of the pan before inverting the cake onto a serving plate. Allow it to cool slightly before serving.

Follow these steps, and you’ll have a scrumptious Nectarine Upside Down Cake that everyone will love!