Combine graham cracker crumbs, sugar and butter; press firmly into bottom of ungreased 12X7-inch or 13X9-inch baking dish.
Combine sweetened condensed milk, lemon juice, yogurt, marshmallows and nuts in large bowl. Spread half of the mixture over crust. Top with half of the bertries, remaining yogurt mixture then remaining berries.
Cover: Freeze 6 hours or until firm. Let stand 10 mintes; cut into squares.