Upside Down Plum & Blackberry Cake - Chef In You

Ingredients

• 4 medium-size ripe plums, pitted and sliced (I did not peel)
• 1 cup frozen (or fresh) blackberries
• 1/2 cup coarsely chopped walnuts
• 1/4-1/3 cup (packed) dark brown sugar, to taste (my plums were v.sweet hence used little less than 1/4 cup)
• 2 tsp lemon zest
• 1 tbsp cornstarch
• 2 tsp freshly squeezed lemon juice
• 3/4 cup whole wheat pastry flour
• 1/4 cup fine yellow cornmeal, preferably stone ground
• 1/3 cup white sugar
• 1-1/4 tsp baking powder
• 1/4 tsp baking soda
• 1/4 tsp salt
• 1/2 tsp ground cinnamon
• 1/4 tsp ground allspice
• 1/4 tsp ground anise
• 1/2 cup well shaken buttermilk
• 2 tbsp unsweetened apple butter
• 1 tbsp butter, melted
• 2 egg whites or 1 whole egg
• 1 tsp vanilla extract