Preheat waffle iron per manufacturer's instructions.
In a large mixing bowl, use a whisk to sift together flour, sugar, cocoa, baking powder, baking soda and salt. Add chocolate chips, mixing until evenly distributed.
In a separate bowl, whisk together buttermilk, butter, egg yolks and vanilla. Make a well in the center of the dry ingredients add to dry ingredients mixing just until fully moistened.
Using an electric mixer on high speed, beat egg whites with cream of tartar until stiff peaks form. Gently fold into batter. Batter will be lumpy.
Spray both sides of the preheated waffle iron with nonstick cooking spray. Pour in enough batter to lightly but fully cover the surface of the iron, about ¾ cup, depending on the size of the waffle iron.
Close iron cooking until waffles have crisp and golden exteriors, about 5 minutes or according to manufacturer recommendation.
Cook waffles in batches. Repeat spraying the waffle iron with cooking spray as needed. Keep waffles warm between batches in a 200°F oven in a single layer on a sheet pan, until serving.
Serve immediately drizzled with chocolate syrup, whipped cream and fresh berries.