Mix together the butter and sugars until creamy. Add the egg whites and mix well.
Mix in the vanilla extract and rum.
Add flour, baking soda and salt and mix until combined.
Stir in the chocolate chips and mix.
Using a tablespoon, drop mix onto a cookie sheet lined with parchment paper. Bake at 350 for 10-12 minutes, until brown. Let rest for a few minutes before transferring to a plate.