12small plumsenough to cover the bottom of your pan.
for the caramel:
for the cake:
6Tbspbutterat room temperature
1Tbspvanilla pasteor extract
1cupplus 2 Tbsp flour
oven to 350F
Grease a 9" nonstick cake pan. Fit the plum halves, cut side down, in the bottom of the pan. Try to fit as many in as you can without crushing them.
Put the sugar and water in a small saucepan. Stir to combine and heat to a boil. Without stirring, boil until the syrup thickens and turns a medium amber color. Be careful, this caramel will be extremely hot. Pour the caramel over the plums.
For the cake, cream the butter and the 3/4 cup sugar together. Add the eggs, one at a time. Then add the sour cream and vanilla.
Whisk the flour, baking powder and salt together and add to the wet ingredients. Mix just until they are combined.
Pour the batter over the plums, and spread out evenly.
Bake for 30-40 minutes until a toothpick comes out clean. I like to place a baking sheet under the pan to catch any potential spills.
Let the cake cool for about 15 minutes, and then flip it over. The best way to do this is to cover the top of the pan with a plate, and then in one swift move flip the whole thing over.
~~~~adapted from Ina Garten
https://theviewfromgreatisland.com/caramelized-plum-upside-down-cake/ July 20, 2013