Heart Healthy Chocolate Angel Food Cake

Ingredients

• 1/2 cup all-purpose flour
• 1/2 cup whole wheat flour
• 1 1/2 cups sugar
• 1/4 cup unsweetened cocoa powder
• 1/2 tsp ground cinnamon
• 1/8 tsp salt
• 12 egg whites, at room temperature
• 2 tsp cream of tartar
• 1 cup low fat vanilla yogurt
• 1 qt strawberries, hulled and sliced