Chop pecans.

Combine pecans, flour, brown sugar, and melted butter to form a crumb mixture.

Spread the crumb mixture into a 9x13x2-inch pan.

Bake at 350 degrees Fahrenheit for 20 minutes, stirring occasionally.

Remove from oven and cool completely.

Remove 1/3 of the crumb mixture and reserve for topping.

Spread the remaining crumb mixture evenly over the bottom of the pan.

Beat egg whites until stiff peaks form.

Gradually add sugar and beat for 5 more minutes until glossy.

Gently fold in lemon juice, orange-flavored liqueur, and drained thawed strawberries.

Fold in the frozen whipped topping.

Spread the strawberry mixture evenly over the crumb crust.

Sprinkle the reserved crumb topping over the strawberry mixture.

Cover the pan and freeze for at least 6 hours, or until solid.

Remove the dessert from the freezer and let it stand at room temperature for 20 minutes before serving.

Cut into squares and serve.