1. To prepare glaze, combine 1/4 cup sugar and 1/4 cup water in a saucepan; bring to a boil. Cook until reduced to 1/3 cup (about 1 1/2 minutes). Remove from heat; stir in liqueur. Cool.
2. Preheat oven to 350°.
3. To prepare cake, combine 1 cup sugar and eggs in a large bowl; beat with a mixer at high speed until thick and pale. Beat in 1 cup water, rind, juice, and oil. Stir in breadcrumbs, walnuts, dates, and salt; let stand 3 minutes.
4. Beat egg whites with a mixer at high speed until soft peaks form using clean, dry beaters. Gradually add remaining 1/4 cup sugar, 1 tablespoon at a time, beating until stiff peaks form. Stir one-fourth of egg white mixture into batter. Gently fold remaining egg white mixture into batter. Gently spoon mixture into a 13 x 9–inch baking pan coated with cooking spray.
5. Bake at 350° for 45 minutes or until golden brown. Remove from oven. Pierce top of cake with a wooden pick. Brush glaze over warm cake. Cool on a wire rack 2 hours.