Preheat oven to 425°.
Pour condensed milk into a 1-quart baking dish; cover and place in bottom of a broiler pan. Add hot water to pan to a depth of 1 inch. Bake at 425° 45 minutes or until milk is thick and caramel colored. Remove dish from pan; uncover and cool to room temperature.
Reduce oven temperature to 325°.
Combine sugar and 1/4 cup water in a small, heavy saucepan, and cook over medium-high heat until sugar dissolves, stirring frequently. Continue cooking 5 minutes or until golden, stirring constantly. Immediately pour into a 9-inch round cake pan coated with cooking spray, tipping quickly until caramelized sugar coats bottom of pan.
Spoon condensed milk into a large bowl. Add 2% milk, eggs, egg whites, and vanilla extract; stir with a whisk until well blended. Strain the milk mixture through a fine sieve into prepared pan, and discard solids.
Place cake pan in bottom of broiler pan; add hot water to pan to a depth of 1 inch. Bake at 325° 40 minutes or until a knife inserted in the center comes out clean. Remove from oven, and cool the flan to room temperature in water bath. Remove cake pan from water bath, and cover and chill at least 3 hours or overnight. Loosen edges of flan with a knife or rubber spatula. Place a plate, upside down, on top of cake pan; invert flan onto plate. Drizzle any remaining caramelized syrup over flan.