Combine the heavy cream and lavender in a small pot. Heat just to boiling, stirring often, then remove from heat.
Let steep until cooled to room temperature.
Strain out lavender flowers and refrigerate cream for several hours, until completely chilled.
When you are ready to serve the cake, combine the lavender infused cream, powdered sugar, and vanilla in a mixer fitted with a whisk, and whip for several minutes until soft peaks form.
Plum Upside Down Cake
Preheat the oven to 350°F (176°C)
Liberally grease a 9 or 10 inch cast iron skillet, or other pan of similar size, with half of the butter. Yes, you heard me right, half of the butter. It would be sad if your cake stuck to the pan.
Sprinkle the bottom of the skillet with the brown sugar and lemon zest, then add the plums in a single layer, cut side down.
Whisk together the remaining butter, yogurt, eggs, sugar, and lemon juice.
In a separate bowl, combine the flour, baking soda, salt, and cinnamon.
Add the liquid mixture to the flour mixture, and stir gently to combine.
Pour the batter into the skillet, on top of the plums, smoothing and leveling the top.
Bake for 50-60 minutes, or until a toothpick stuck in the center comes out clean.
Let cool for only about 5 minutes.
Put a plate that is larger than the skillet over the top. Using hot pads, carefully flip the cake over and gently lift the pan off the cake.
It’s common for some of the fruit to stick to the pan. As long as the cake is intact, you can do a bit of fruit repair and no one will ever know. Serve with the lavender whipped cream.
Notes
This recipe is loosely based on Plum Rosemary Upside-Down Cake from How to Cook Everything Vegetarian by Mark Bittman (an awesome cookbook!).