Plum Upside Down Cake

How many variations of plum desserts are there? We're well on our way to finding out.. This time my childhood best friend was visiting and we whipped up a plum upside down cake - with only minor burns ensuing. The plums created a delicious pseudo frosting and the sponge cake was perfect.

Recipe adapted from Martha Stewart and Drizzle and Dip

Ingredients
10-12 red or purple plums
6 Tbsp. butter
9 Tbsp. sugar
1/2 tsp. cinnamon
1 c. butter, softened
1 c. sugar
1 c. flour
2 tsp. baking powder
4 eggs
1/2 tsp. almond extract

Directions

1. Cut plums into quarters and remove pits. heat 6 Tbsp. butter in a large saute pan over medium heat until it sizzles. Add plums and cook for 2-3 minutes.
2. Add 9 Tbsp. sugar and cinnamon. Cook stirring frequently, 10-15 minutes. Remove fruit with a slotted spoon and transfer to a baking sheet lined with aluminum foil. Remove pan from heat and save syrup.
3. Butter and flour a 9 1/2 by 2 inch round cake pan. Arrange cut fruit with cut edges down. 
4. Return syrup to medium heat and boil until thick with large bubbles. Immediately pour over fruit and set aside.a
5. Preheat oven to 325. Beat 1 c. butter and 1c. sugar until light and fluffy. Add almond extract and eggs one at a time, allowing to fully combine between each addition.
6. Pour over plums and cook 1 hour.
7. Let cool, run a knife around the outside edge and invert.