Divide the fruit jam between 4 slices of bread, spreading a small circle onto the center of each slice.
Divide the peanut butter onto the other 4 slices of bread.
Create peanut butter and jelly sandwiches. Use the cutter piece of the Uncrustables cutter to create circles out of each sandwich. Discard the crusts.
Carefully turn the cutter over with the sandwich still in it. Place the sealer piece onto the sandwich, aligning the arrow of the sealer piece with the arrow of the cutter piece.
Press the sealer down firmly and hold it for about 15 seconds. Carefully release the sealer and remove the sandwich from the cutter piece.