3smallplums, pitted and sliced into 1/4-inch thick slices
2tsplemon juice
1/2tspcinnamon
1 1/2tspsugar
2Tgranulated sugar, to dust pan
2Tturbinado sugar (raw sugar) or coarse sparkling sugar, for topping
Instructions
Melt butter in a light-colored, heavy bottomed saucepan on medium heat, occasionally swirling the pan or stirring until the butter is amber-colored and smells nutty. (See my brown butter post here for more detailed instructions). Immediately pour brown butter into a separate bowl and allow to cool for about 25 minutes.
Preheat oven to 350°F.
Line a 9-inch cake pan (at least 2 inches tall) with parchment paper so the paper reaches all the way up the sides and hangs over the edges. Spray with nonstick baking spray or grease with butter or oil. Sprinkle with the 2 T of granulated sugar, tilting the pan to coat the bottom and up the sides of the parchment with sugar. Set aside.
In a small mixing bowl, combine the sliced plums, lemon juice, cinnamon, and 1 1/2 tsp sugar, stirring until all of the plum slices are coated with cinnamon-sugar. Set aside.
In another small mixing bowl, combine the cornmeal, flour, baking powder, and salt, stirring to combine. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment (or in a large mixing bowl using a hand mixer or a whisk and some elbow grease), mix the cooled brown butter and both sugars until combined. Then add the eggs and beat on medium speed for 1-2 minutes, or until light-colored and fluffy. Then add the vanilla and rum and mix until combined.
Add the cornmeal-flour mixture to the bowl and mix just until combined. Scrape batter into the prepared cake pan and use a spatula to spread it to the edges and smooth the top. Arrange the plum slices on top, then sprinkle with the 2T turbinado sugar.
Bake for 45-50 minutes, or until cake is golden brown and a toothpick inserted into the center comes out clean or with a few crumbs. Move to a cooling rack to cool, then remove cake from pan, slice, and enjoy! Lovely on its own, but could also benefit from a dollop of lightly-sweetened whipped cream.