3. Step
Cut away cardboard packaging from 1 carton of ice cream with scissors. Slice ice cream crosswise into 1-inch-thick rounds with a long knife. Arrange slices over crumbs, cutting smaller pieces to fill gaps. Cover ice cream with another 1 1/3 cups crumbs. Repeat with second container of ice cream, and top with remaining crumbs. Freeze until firm, at least 1 hour.