Preheat oven to 350°.
Cut butter into brown sugar with a pastry blender until crumbly. Stir in oats and next 5 ingredients.
Combine egg whites, peanut butter, and condensed milk in a small bowl; stir with a whisk until smooth. Add egg mixture to oats, and stir well.
Press mixture into a jelly-roll pan coated with cooking spray. Bake at 350° for 20 minutes; cool completely. Cut into 28 bars.
NOTE: Bars can be stored in pan or on a plate, covered.