Plum Cornmeal Kuchen

1 cup all-purpose flour
1 cup cornmeal
1 1/2 teaspoon baking powder
1 1/2 teaspoon ground cinnamon
1 stick butter, room temperature
2/3 cup plus 1/4 cup sugar
2 large eggs
2 teaspoon vanilla extract
1/2 teaspoon almond extract
1/2 cup sour cream
5 large plums, halved, pitted, each cut into 8 wedges