Step 1

Preheat the oven to 375 degrees F. Grease a 10-by-1 1/2-inch round baking dish with the butter and sprinkle with 1 tablespoon of granulated sugar.

Step 2

In a small bowl, combine the prunes with 2 tablespoons of Armagnac and microwave on high for 1 minute. Set aside.

Step 3

In the bowl of an electric mixer fitted with the paddle attachment, beat the eggs and 1/3 cup granulated sugar on medium-high speed for 3 minutes, until light and thick. In a small bowl, combine the flour, baking powder, and salt. Combine the cream, vanilla, lemon zest, and 1 tablespoon Armagnac in a glass measuring cup. On low speed, slowly add the dry ingredients to the batter and then add the liquid ingredients, mixing well. Set aside for 10 minutes

Step 4

Distribute the prunes in the prepared pan and carefully pour on the batter. Sprinkle evenly with 1 teaspoon granulated sugar. Bake for 35 to 40 minutes, until the top is golden brown and a toothpick comes out clean. Cool slightly, sprinkle with confectioners' sugar, and serve warm.