Preheat the oven to 350°F Line a 9-inch springform pan with aluminum foil.
Pit and halve the plums and place them, cut sides up, in the bottom of the pan. Set aside.
In an electric mixer, blend the flour, sugar, and oil on low speed until the flour is evenly moistened. Add the eggs and blend thoroughly.
In a small bowl, mix together the baking soda, cinnamon, allspice, nutmeg, ginger, and cloves. Add the spice mixture to the batter in the mixer and blend well. Scrape the sides and bottom of the bowl. Add the vanilla and almond extracts and the salt and mix again.
Pour the batter slowly over the plums. Bake the cake for 50 to 60 minutes, or until a tester inserted in the center comes out clean. Set aside to cool for 15 minutes before inverting onto a serving plate.
Serve the Plum Spice Cake warm with softly whipped cream.