This is a dense, buttery cake dotted with sweet-tart plums that have gone silky in the oven. It takes just a few minutes to get it into the oven, and comfortably knife-wielding kids might like to help by halving the plums and tugging out their pits. The original recipe calls for neither vanilla nor almond extract, but it asks you to sprinkle a teaspoon of cinnamon over the cake before baking, which I did for years, until I discovered that I wasn't that crazy about the cinnamon. I have, however, sprinkled a teaspoon of cardamom over it, and that is delicious.
The recipe calls for "purple plums" and I have always used those oblong Italian prune plums, if I can find them, because the pits come out so nicely but other plums are good too (and maybe even other kinds of juicy fruits altogether).
Heat the oven to 350.
Use an electric mixer (if you have one) to cream together the butter and sugar — or do this all by hand, which is fine.
Now add the eggs, one at a time, beating well after each, and add the extracts too.
Beat in the flour, which you've either sifted or whisked together with the baking powder and salt, and mix until the batter is well combined. (Note: the original recipe has you add the eggs and flour all together, and it turns out I am just too uptight to do it that way, which is good to know about myself).
Now scrape the very stiff batter into your pan: I use a spring form pan that seems to be 9 1/2 inches across, but you could butter and flour a regular cake pan and use that, need be. Use a rubber spatula to even it out; it will make a very shallow layer, and that's fine.
Now onto the plums, which you've already halved, right? Arrange the plum halves skin-side-up in a fancy concentric pattern around the cake. Or else willy-nilly, if you prefer. You will be tempted to put the cut side up because it looks prettier that way - but don't. You want all that lovely plum flesh to bake its juicy way right into your cake.
Now sprinkle the cake with a teaspoon of sugar and pop it in the oven to bake until it looks nice and brown and doesn't jiggle anywhere when you, uh, jiggle it — the recipe says an hour, but mine is always done after 45 minutes; if your pan is smaller (and your batter therefore deeper) it may take a bit longer.
Serve with whipped cream or vanilla ice cream.