- ½ pound (2, sticks) unsalted butter, at room temperature
- ¾ cup superfine sugar
- ¼ teaspoon table salt
- 1 teaspoon vanilla extract
- 3 large eggs, at room temperature
- 3 large egg yolks, at room temperature
- 1½ cups all-purpose flour
- 1½ cup medium-grind yellow cornmeal
- 1 teaspoon baking powder
- 2 tablespoons creme de cassis
- 2 tablespoons apple juice
- 1 tablespoon superfine sugar
- 2 ripe plums, stoned and cut into 1/8-inch slices
- 2 ripe nectarines, stoned and cut into 1/8-inch slices
- 2 cups blackberries
- 1/3 cup mascarpone mixed with
- 1 teaspoon superfine sugar, for garnish (see Note)
- PREHEAT THE OVEN to 350°F. Butter a 9 × 5-inch loaf pan and dredge it with polenta, shaking out the excess.
- TO MAKE THE CAKE: In a stand mixer or with a strong hand mixer, cream the butter, sugar, and salt together until light and fluffy, Add the vanilla. Add the eggs and egg yolks, one at a time, completely incorporating each one before adding the next. Sift in the flour, polenta, and baking powder and mix well. Pour the batter into the pan.
- BAKE FOR 50 TO 55 MINUTES, or until the top springs back and a skewer inserted in the center comes out clean. Run a knife around the pan to release the cake and invert it onto a rack. Allow to cool completely.
- TO PREPARE THE FRUIT: In a medium saucepan, combine the crème de cassis with the apple juice and sugar. Stir over low heat until the sugar has dissolved. Increase the heat and bring the mixture to a boil. Add the plums, nectarines, and blackberries and reduce the heat to a simmer. Cover and simmer for 8 to 10 minutes, or until the fruits are tender. Remove the lid and simmer for 6 to 7 minutes more, stirring occasionally, until the syrup has reduced to coating consistency and the softened fruits are glazed with it.
- CUT THE CAKE into 1-inch slices, place on individual dessert plates, and spoon some of the warm fruit and syrup over each. Top with a dollop of sweetened mascarpone and serve.