Preheat oven to 350 degrees F (176 degrees C).
Cream together Granulated Sugar (1 cup) and Unsalted Butter (1/2 cup). Add All-Purpose Flour (1 cup), Baking Powder (1 teaspoon), Salt (1 pinch), and Egg (2). Beat well for a couple of minutes.
Generously butter a springform pan and sprinkle with sugar.
Add the batter to the pan.
Top the batter with the Black Plum (12), skin side up, and sprinkle lightly with sugar and Ground Cinnamon (to taste). Drizzle with Lemon Juice (to taste).
Bake for 1 hour, or until a toothpick comes out clean.
While the cake bakes, caramelize Granulated Sugar (1/2 cup).
Add Heavy Cream (1 cup) and simmer until smooth.
Add Grand Marnier (1.5 fluid ounce).
Add the plums and simmer until they are heated through, about 2 minutes.
Serve the compote alongside the torte. Enjoy!