To make compote, combine boysenberries and apple juice in a small saucepan; simmer for 5 minutes. In a separate bowl, combine sugar and cornstarch and add to berry mixture, gently stirring until it boils. Remove compote from heat and let it cool slightly until it thickens.
To make pancakes, dissolve baking soda in buttermilk in a small bowl; set aside. In a larger bowl, combine flour, cinnamon and sugar. Add buttermilk mixture, egg whites and vanilla, and blend. Spray griddle with vegetable-oil cooking spray. Ladle pancake mixture onto griddle and cook until pancakes are light brown on both sides. Serve with boysenberry compote.
