Carefully slice through the middle to create four halves.
Cut the halves into triangles.
Toast the cut side for 1-2 minutes.
Notes
You can really make any size or shape you want when it comes to melba toast. If you wanted something a little more festive, then you could use a star or Christmas tree cookie cutter.
To make it really easy to slice through the bread, do it when it is still warm.
Make sure to keep and eye on your melba toast when it goes back in the oven, because they can burn very quickly because of how thin they are.
Don't throw away the crusts. You can use them to make your own breadcrumbs.