Lay out all 12 slices of bread on a clean work surface.
Spread peanut butter evenly over each slice, leaving a small border around the edges. Spreading peanut butter on both slices helps keep the bread from becoming soggy.
Spread the grape jelly over 6 of the peanut butter-coated slices.
Top each jelly-covered slice with one of the remaining peanut butter-coated slices to form 6 sandwiches.
Place a sandwich cutter over each sandwich and press firmly to seal the edges. While the cutter is still in place, remove the crusts.
Lift off the cutter and place each sandwich into an individual freezer-safe sandwich bag.
Freeze until ready to enjoy. Thaw at room temperature or pack frozen in a lunchbox where it will thaw by lunchtime.