How to Make It
Place a knife in a container of hot water to heat blade. Run outside of ice cream container briefly under hot water just until edges of ice cream in container are softened. Invert ice cream onto a cutting board, and remove and discard container. Turn ice cream block on its side. Remove hot knife from hot water, and wipe knife dry. Cut ice cream block crosswise into 6 (3/4-inch-thick) slices, rinsing knife in hot water and wiping dry after each cut. Place ice cream slices on a rimmed baking sheet, and freeze until firm, about 30 minutes.
Place cereal in a shallow bowl. Remove ice cream from freezer. Holding 1 ice cream slice by the middle, roll edges of slice in cereal. Using a 1-inch round cutter, remove center of each ice cream slice. Place on bottom doughnut half, and cover with top doughnut half. Repeat with remaining ice cream slices, cereal, and doughnuts. Serve immediately, or freeze until firm, about 30 minutes.