When I first moved down to the Bay Area from Portland, Oregon, I had a deep love of food but not a deep understanding of it. My boss at the time, Rosie, was obsessed with stone fruit season and would get so excited for it to come around. The first time she mentioned that fact to me, I made a note to look up what "stone fruit" meant when I got back to my computer. It is crazy for me to think that was only a few years ago.
I can't say that I have ever been a fan of pineapple upside-down cake but the many variations I have had along the way have been pretty knock out. This recipe is a variation from Bi-Rite Market's Eat Good Food Cookbook.
1 1/2 sticks unsalted butter
3/4 cup packed brown sugar
8 small plums (a little over a pound)
1 cup AP flour
1/4 cup rye flour (if you don't have you can sub for AP or wheat)
3/4 cup granulated sugar
2 teaspoons baking powder
1 teaspoon kosher salt
3 large eggs
1/2 cup buttermilk
1 teaspoons vanilla extract
Preheat the oven to 350 degrees and make sure a rack is in the center. Melt half of the butter (6 tablespoons) on medium heat and stir in the brown sugar and 1/2 teaspoon of salt. Let this melt and bubble together for about 5 minutes until the texture becomes smooth. The butter will never completely combine with the sugar and that is totally normal.
Pour the butter/sugar mixture into the bottom of a cake pan (I used a round 9" x 3" pan but you can use what you've got at home). I used a spring-form pan and it ended up leaking some of the butter/sugar combo, so I would recommend using a regular ol' cake pan. Slice the plums into the desired shape and lay them on top of the butter/sugar mix in the bottom of the pan. You can get creative here or just plop them in. Just make sure all of the butter/sugar mixture is covered in fruit. Now, set this aside so you can make the batter.
In a medium bowl, sift together the flour, baking powder and 1/2 teaspoon of salt. In a stand mixer with a paddle attachment, blend the rest of your butter and granulated sugar. As the mixer is running, add the eggs one at a time. Mix until smooth and slowly add the dry ingredients in two parts, mixing in between. Then, add the vanilla extract and buttermilk. Mix everything together on high for 1-2 minutes until mesmerizingly smooth and fluffy.
Carefully spoon the batter over the fruit, being careful not to move the fruit around. Bake for 1 hour or into you can run a knife or skewer through it and it comes out clean. Invert onto a plate and if it gives you a hard time, give a gentle shake up and down to get it moving. Make sure to slide it out when the cake is still warm. Let cool before cutting into it and enjoy!