Nectarine Upside Down Cake

I apologize for the ugliness of this cake but what it lacks in looks it sure makes up in taste. I had a bunch of nectarines that needed to be used but I didn't think you could bake anything with them. I googled nectarines and found this recipe. It was truly delicious. It was also my first attempt at making caramel....I think this may be a time where butter must be used instead of margarine. I am a die hard butter fan but with the summer heat the butter went moldy and Mike convinced me to switch to margarine. That will be changing soon. I found this recipe here and I am excited to read that this would be a good cake for peaches and plums. The original recipe didn't mention taking the skin off. I want to make this again and take the skin off but I wonder if having the skin helped keep the moisture in the fruit. Let me know if you make it what you do.

Ingredients
Caramel:
6 tablespoons butter plus additional for the pan
1 cup sugar
4 to 6 fresh nectarines, halved, and pitted (peaches, apricots, or plums can be substituted)

Cake:
1 cup granulated sugar
1/3 cup melted butter
2 eggs
1 and 1/2 cups all-purpose flour
2 teaspoons baking powder
1 teaspoon salt
1/2 cup buttermilk
2 teaspoons vanilla extract

Directions
Butter a 10-inch cake pan, line the bottom with parchment paper, and butter the paper. Place 2 tablespoons water and sugar in a saucepan, and stir together. Cook over high heat, swirling the pan (do not stir), until the mixture turns a golden caramel color. Immediately remove the pan from the heat, and whisk in the butter (be careful; the mixture will foam). Pour the caramel into the bottom of the prepared cake pan. Cover the bottom of the pan with the nectarine halves, cut-side-down.

Preheat the oven to 350 degrees. Add the sugar and melted butter to the bowl of a mixer fitted with a whisk attachment, and beat until combined. Add eggs, and whisk until the mixture is light and fluffy. Sift together flour, baking powder, and salt. Stir the buttermilk and vanilla extract together. With mixer set on low speed, add the dry ingredients by thirds, alternating with the liquid ingredients, to the butter mixture. When it's all fully blended, pour the batter into the pan over the nectarines and bake, rotating it front-to-back after the first 15 minutes, for about 50 minutes or until the cake is golden brown and springy to the touch. Remove from the oven, and allow to sit for about 10 minutes before inverting onto a platter and peeling off parchment paper.