1. Heat oven to 350 degrees F. Coat sides of 2-quart baking dish with cooking spray.
2. Beat together egg yolks, lemon juice, rind, butter and 1-1/4 cups sugar in large bowl for 2 minutes or until blended. Add milk, flour and salt; beat at low speed just until combined.
3. Beat egg whites with electric mixer until soft peaks form. Beat in remaining 1/2 cup sugar; beat until glossy peaks form, about 2 minutes.
4. Fold whites into lemon mixture until blended. Scrape into prepared dish; set on baking sheet.
5. Bake in 350 degree F oven for 40 minutes or until wooden pick inserted in cake center comes out clean. Serve warm. Makes 10 servings.