Preheat the oven to 400°F.
In first bowl, combine all dry ingredients, including chocolate chips.
In second bowl, whisk together wet ingredients: whey, oil, and vanilla.
Pour wet ingredients into the dry ingredients and stir to combine.
Fill muffin cups 2/3.
Sprinkle the tops of the muffins with the coarse sugar, if desired.
Bake the muffins for 18 to 20 minutes. Insert a toothpick into the center of a muffin. If it comes out clean, muffins are fully baked.
Cool and serve warm or at room temperature.
Adapted from King Arthur Flour.