Preheat oven to 350F (175C). Beat the eggs and sugar in a medium bowl. Add the flour and baking soda. Boil the milk with the butter, and add that to the flour and sugar mixture. Stir in the vanilla. Pour the batter into a 9" round pan. Arrange plum slices on the top. Bake
for 45-50 minutes or until browned and an inserted toothpick comes out clean. If using a different sized pan (like 9x13 baking dish), adjust cooking time accordingly.