• 3/4 cup unsalted butter, divided
• 1/4 cup brown sugar
• 2 tsp balsamic vinegar
• 1 1/2 pounds pitted fresh cherries
• 1 1/4 cups flour
• 1/4 cup stone-ground polenta or cornmeal
• 2 tsp baking powder
• hefty pinch salt
• 1 cup sugar
• 2 large eggs, separated
• 1 tsp vanilla
• 1/2 cup milk
• 1/4 tsp cream of tartar

Preheat oven to 350°.

Mix 1/4 cup butter with brown sugar and vinegar in 10″ skillet. Stir over medium heat until butter melts and sugar dissolves. Add cherries and bring to boil. Remove from heat.

Whisk flour, cornmeal, baking powder, and salt together. Beat remaining 1/2 cup butter in large bowl with sugar and beat until pale and fluffy. Beat in egg yolks and vanilla.

Add flour mixture alternately with milk in 2 additions mixing until just blended. Beat egg whites in another bowl with cream of tartar and beat until whites are stiff but not dry. Fold 1/4 of whites into batter to lighten slightly. Carefully fold in remaining whites. Spoon batter over cherries in skillet, then spread evenly to cover cherries.

Bake cake until top is golden brown and tester inserted into center comes out clean, about 45 minutes. Cool in skillet on rack 5 minutes. Place cake plate atop skillet and carefully flip. Leave skillet atop cake 5 minutes. Remove skillet. Rearrange any cherries that may have become dislodged. Cool at least 45 minutes.