Prune And Armagnac Cake

• 2 egg (white)
• 1 pitted prunes quartered
• 1/2 cornmeal more (plus)
• 110 gr armagnac
• 100 gr sugar
• 60 ml nonfat yogurt (plain)
• 32 gr all purpose flour (white)
• 30 ml vegetable oil
• 14 gr butter softened
• 9 gr pure vanilla extract