Upside Down Pflaumenkuchen

Upside Down Pflaumenkuchen
The sample above was made with plums from Filippo's mom's tree; we devoured it in a single Study Break.

Original recipe yield: 1 - 9 inch round cake.
Prep Time: 30 Minutes
Cook Time: 40 Minutes
Ready In: 1 Hour 10 Minutes

Ingredients:
1 cup all-purpose flour
1/4 cup whole-wheat flour
1+1/2 teaspoons baking powder
1/4 teaspoon salt
1/2 teaspoon cinnamon
scrape or two of real nutmeg (please don't use pre-ground)

3 tablespoons butter
1/4 cup brown sugar

1/3 cup butter
1/2 cup white sugar
1 large egg (extra-large also ok)
1 teaspoon vanilla extract
3/4 cup milk
7 black plums, pitted and thinly sliced (you may need more or less than this)

Directions:
1) Preheat oven to 350 degrees F (175 degrees C). Grease a 9 inch cake pan. Combine the flour, baking powder, salt and spices. Set aside.
2) In the prepared pan, combine 3 tablespoons butter and brown sugar. Place pan inside the preheated oven until the butter melts and begins to bubble. Set aside. In a large bowl, cream together the 1/3 cup butter and 1/2 cup white sugar until light and fluffy. Beat in the egg, then stir in the vanilla. Beat in the flour mixture alternately with the milk, mixing just until incorporated.
3) Arrange plums in concentric circles in the prepared pan, overlapping slightly. Pour batter overtop of the fruit, covering fruit completely. Bake in the preheated oven for 30-40 minutes --until lightly brown on top and a toothpick inserted into the center of the cake comes out clean.
4) Allow to cool in the pan for 15 minutes before flipping and serving.