I used a few pieces of cherry and a piece of purpleheart but any hardwood would work. In addition to the wood you'll need some waterproof glue (I used Titebond III) and a food-safe finish (I used Good Stuff).
Let's get started.
Step 1: Prep the wood
Step 2: Arrange the wood and glue it together
Move the wood to some scrap paper, flip each piece on its back and smear some glue across every piece except one (the last one in line gets glue from its neighbor). I've apparently learned nothing since kindergarten since this step always ends with my fingers coated in white glue.
Flip the pieces back to standing and make sure they all line up before clamping everything together. I used a few pieces of scrap wood to prevent the clamps from denting the cutting board.
Wipe off any excess glue after everything is clamped.