Combine dry ingredients in a large bowl and whisk to combine. Set aside.

By hand or in a the bowl of a standing electric mixer, beat egg whites until the peaks are stiff but not dry. Set aside.

In another large bowl, whisk together buttermilk, butter, egg yolks, and vanilla. Pour wet ingredients over the dry ingredients and gently mix until just combined. Stir in chocolate chips. Finally, fold egg whites into the batter.

Spoon batter by 1/4 cupfuls onto the griddle, nudging the thick batter into rounds. Cook until the tops are speckled with bubbles that begin to pop before flipping. Continue cooking until the underside turns lightly brown and the center has mostly set. Serve immediately or keep warm in an oven heated t0 200º F.