Here's the recipe:
Lemon Raspberry Upsidedown Cake
Pan: 9" round cake pan
11 TBS (155 g) unsalted butter, softened
1 1/3 c (267 g) granulated sugar
12 oz (350 g) raspberries, fresh or frozen (if frozen, do not defrost)
1 2/3 c (168 g) cake flour, sifted
1 t baking powder
1/4 t salt
1 T lemon zest
2 large eggs
1/2 c (120 g) sour cream
1 t lemon extract
Preheat the oven, then prep the pan by smearing 3 T (42 g) of the softened butter onto the bottom and sides of a 9" round cake pan. Go ahead and use it all, even if you leave some clumps. Over the butter, sprinkle 1/3 c (67 g) of the sugar, creating a thin layer, then spread the raspberries over that. NOTE: I used frozen and waited until the batter was ready before doing this, but it's up to you.
In a small bowl, whisk together the cake flour, baking powder, and salt, and set aside.
Put the remaining 1 c (200 g) of sugar into the bowl of a stand mixer, or in a large bowl if using a hand mixer, and rub in the 1 T of lemon zest. Add the remaining 8 T (113 g) butter and cream on medium-high speed until lighter in color and fluffy, about three minutes.
Add in the eggs, one at a time, mixing well for 30 seconds between each egg. Don't forget to scrape the sides of the bowl!
Add the lemon extract and sour cream, and beat until all traces of sour cream have been incorporated.
Stop the mixer and fold in the dry ingredients gently, but thoroughly, until no streaks of dry are apparent.
Spread the batter on top of the prepared pan and slide into the oven.
Bake for 45–50 minutes, until the cake begins to pull away from the sides of the pan, the top springs back lightly when touched, and a toothpick inserted into the center (but not all the way down to the fruit) comes out clean.
Remove pan to a rack and let cool 10 minutes, then turn the cake out to cool completely.
Gorgeous on its own, the cake keeps well, and gets a bit better with age, for a few days. Luster fades around day three.