Chill a large mixing bowl at least 15 minutes.
Preheat oven to 400°F. In a bowl combine flour, oats, brown sugar, and salt.
Cut in butter until pieces resemble coarse crumbs.
Stir in nuts. Pat lightly into a 13 x 9-inch pan.
Bake 15 minutes or until golden. Stir to crumble; let cool.
Remove half the crumbs; set aside.
Spread remaining half evenly across bottom of the baking pan.
Place ice cream in the chilled bowl.
stir to soften. Stir in fruit. Spread evenly over crumbs in pan.
Top with reserved crumbs. Cover; freeze 6 hours or until firm.
Keep it at room temperature 5 to 10 minutes before cutting.