Preheat oven to 325 degrees F. Line a baking sheet with parchment paper. In a food processor, pulse together graham cracker sheets and walnuts or pecans into fine crumbs.

Pour mixture into a bowl, add butter, flour, and 1/2 cup of sugar, and mix together with a fork until thoroughly combined. Spread the crumb mixture in an even layer on the baking sheet.

Bake for 15-20 minutes, stirring the crumbs halfway through. Remove from the oven and set aside to cool.

In a medium bowl, using an electric hand mixer, beat egg whites and 1/2 cup of sugar until frothy, about 3 minutes.

Add heavy cream and beat until soft peaks form.

Add cream cheese and lemon juice, and mix until creamy. Gently fold in chopped strawberries.

Press half of the crumb mixture into the bottom of a 9 x 13 pan.

Spread strawberries and cream mixture on top and sprinkle remaining crust/crumb mixture on top.

Freeze for 3-6 hours, or overnight.

When ready to serve, let it sit out for 10 minutes before cutting into squares. Garnish with additional strawberries if desired.