1. Dip half the tea biscuits into coffee, then place into lined nine- by 13-inch pan in single layer.
2. Beat egg whites until stiff. Add sugar, beating until peaks form. Set aside.
3. Beat whip cream and vanilla until peaks form, folding into beaten egg whites. Pour over biscuits.
4. Dip remaining biscuits into coffee. Arrange on top of ice cream. Freeze.
5. Cut between and around corresponding biscuits.