Preheat the oven to 375 degrees. Grease a muffin tin, plus 4-5 cups of a second tin, with butter or olive oil.
Place the egg whites in a large mixing bowl or stand mixer. Beat until they form stiff peaks.
Place the egg yolks in a medium mixing bowl. Whisk them together with the salt, white pepper, chives, mustard, and olive oil. Gently fold the crab into the egg yolk mixture.
Fold one-third of the eggs whites into the crab mixture to loosen it up, then fold in the rest of the egg whites. Do not over fold, as you want to keep lots of volume. Some white streaks can still remain. Use a third-cup measure to scoop the mixture into the prepared tins. Bake for 12-15 minutes, or until they are puffy and lightly browned on the tops. Serve hot or at room temperature.