• Preheat the oven to 350 degrees.

For the Topping:

• Wash and dry your plums. You’ll want enough plums that when cut into wedges, they cover the bottom of the cake pan. Mine were quite small, so I used about 6 plums.
• In a small microwave-safe bowl, melt the 6 tablespoons of butter.
• Add the brown sugar and stir well to combine.
• Using a silicone spatula, scrape the mixture into the bottom of the cake pan. No need to butter or put parchment on the bottom of your pan.
• Place the plum wedges in the bottom of your pan, in a circular pattern. You’ll be able to get more wedges in the pan instead of just dumping them in, and it will look very pretty. Set pan aside while you prepare the cake.

For the Cake:

• In a medium bowl, sift your dry ingredients (flour, spice, baking powder, baking soda, and salt).
• Add the vanilla extract to the milk.
• In a stand mixer (a hand-held mixer would work, too), add the room temperature butter and whip on medium speed for 2 minutes to aerate. Add the sugar and whip again for 2 minutes more.
• Lower the speed and the eggs one at a time, beating well after each addition.
• Add the ricotta cheese and blend well.
• On low speed, add a third of the flour mixture and blend gently. Add half of the milk mixture and blend again. Add another third of the flour mixture, then the other half of the milk mixture, blending gently. Add the last of the flour and combine completely on low.
• Using a silicone spatula, scrap the batter over the plums.
• Place the pan in the preheated oven and bake for 45 minutes. Check for doneness and bake longer if necessary, checking after 3 to 4 minutes each time so you don’t overbake the cake. In my oven, it took 1 hour and and 2 minutes.
• Once a toothpick inserted in the center comes out with a few crumbs, remove from the oven and allow to cool for 20 minutes. Do not allow cake to completely cool! It will not invert as easily.
• Using a very sharp knife, run the blade around the perimeter of the cake to loosen the sides.
• Time for the fun – Place your cake platter or cake stand over the cake pan. Be careful; your cake pan is still hot. Very carefully, hold the platter or stand firmly on top of the cake pan, and using both hands, flip the two over together, so that the cake is now upright. Gently lift the cake pan off to reveal your beautiful dessert!
• Allow to cool for another 20 to 30 minutes or to room temperature before slicing.
• It is best to refrigerate any leftovers if not eating within a day.