CAKE: Mix apples and sugar and let stand for 1 hour or longer. Add eggs, flour, soda, cinnamon, salt and nuts. Mix and put into a 9x13-inch greased pan. Bake at 350-degrees for 45 minutes. TOPPING: During last 15 minutes of baking time, mix together brown sugar, granulated sugar, 6 tablespoons flour and water. Bring to a boil, stirring often. Turn down heat and simmer for 15 minutes. Remove from heat and add butter, vanilla and nuts. Pour over the cake while hot. Serve warm or cold.