1/2 cup granulated sugar
1/4 tsp ground nutmeg
3 tbsp butter, melted
1 lb plums, halved, pitted and each half cut into 4 pieces
1 cup all-purpose flour
1/3 cup cornmeal
3 tbsp sugar
1 tbsp freshly grated lemon peel
1 1/4 tsp baking powder
5 tbsp + 2 tsp cold butter, cut into pieces
1/2 cup milk
1 large egg
Preheat oven to 400 degrees. Cover the bottom of a 9-inch round baking pan with waxed paper; set aside.
To make the topping: Mix the sugar and the nutmeg in a small mixing bowl; add the melted butter. Spread the mixture over the waxed paper in the baking pan. Arrange the plum slices in pinwheel fashion over the sugar mixture.
To make the biscuit: Put the flour, cornmeal, sugar, lemon peel, and baking powder in a food processor and pulse to mix. Add the butter and pulse just until coarse crumbs form. The the milk and egg then pulse briefly until a dough forms. Spoon the dough over the plums in the pan. Spread to the edges of the pan so the plums are completely covered.
Bake at 400 degrees for 26 to 28 minutes or until the biscuit is lightly browned and the fruit bubbles up around the edges. Cool in the pan on a wire rack for 10 minutes. Invert the serving plate over the cake pan. Protecting your hands with oven mitts or potholders, hold the plate and pan together and invert the cake onto the plate. Remove the pan and waxed paper. Cut the cake and serve warm.