Heat oven to 350 degrees.

Cream the sugar and butter in a bowl. Add the flour, baking powder, salt, and eggs and beat well.

Spoon the batter into a springform pan of 20, 22, or 24 cm (8, 9 or 10 inches). Place the plum halves skin side up on top of the batter. Sprinkle lightly with sugar and lemon juice, depending on the sweetness of the fruit. Sprinkle with about 1 tablespoon of light brown, raw sugar or plain white sugar.

Bake 1 hour, approximately. Remove to a cooling rack.