In a bowl, combine the flour, brown sugar, butter, and walnuts. Mix together and spread out on a large cookie sheet (I used a 15x10x1" baking sheet). Cook for about 15 minutes, stirring 2-3 times during baking. Let cool for about 5-10 minutes, remove 1/2 cup to use for later, and press the rest of the nut mixture into a 9x13" baking pan that has been sprayed with non-stick cooking spray.
In another bowl, mix together strawberries, sugar, and lemon juice. Fold in the Cool-Whip and spread over the cooled crust. Top with the reserved 1/2 cup of nut mixture, sprinkled over the strawberry filling.
Cover and place in the freezer for at least 6-8 hours.