1. Preheat oven to 350 degrees Fahrenheit. Line bottoms of two nine-inch round cake pans with Gefen Parchment Paper. Lightly grease paper.
2. Combine flour, baking powder, and salt in a medium-size bowl. Set aside.
3. Beat margarine and sugar in a large bowl with an electric mixer, at medium speed, until light and fluffy.
4. Add egg whites, two at a time, beating well after each addition. Add vanilla extract; beat until blended.
5. With electric mixer at low speed, add the flour mixture to the batter, alternating with the pareve milk, beating well after each addition. Pour batter evenly into prepared pans.
6. Bake 25 minutes or until wooden toothpick inserted into the center comes out clean.
7. Cool layers in pans for 10 minutes. Loosen edges and invert layers onto a rack to cool completely.