Preheat the oven to 350°. Butter a 9-inch cake pan and line it with parchment paper.

In a large bowl, whisk together the flour, almond flour, baking powder and salt.

In another bowl, whisk together the oil, egg, half and half, lemon zest, lemon juice, 1 cup of sugar and the almond extract.

Add the oil-egg mixture to the flour mixture, and whisk until just combined.

Pour the batter into the prepared pan. Arrange the plum halves, cut side up, on top of the batter.

In a small bowl, stir together the almonds, 2 tablespoons sugar and softened butter; mix well. Dot the almond topping over the cake.

Bake until the topping is golden brown and a cake tester inserted into the center of the cake comes out clean, 35 to 45 minutes. Allow the cake to cool for 20 minutes. .

While the cake is cooling, prepare the whipped cream. Place the heavy cream, vanilla bean paste and sugar in a large, cold stainless steel bowl. Using a large whisk or an electric mixer, whip the cream until medium peaks form.

Cut the cooled cake into wedges, and top with a dollop of the vanilla cream and Almond Brittle.