The picture is very small, so this is just a wild guess:
One can used a graphics program such as Photoshop to make a letter appear to be on fire. Then one can print that letter on a icing sheet or on wafer paper and apply it to a cake. Unfortunately, those are usually white backgrounds, so I'm not sure how you would apply it to black.
I haven't quite mastered that technique. I was thinking maybe I should create a silicone mold of the letter "e" . Then maybe pouring Isomelt in yellow, red and orange. Then pulling edges to resemble fire.
Can't find any techniques on YouTube that could help.
Print this photo to the size you need, put it under a piece of wax paper. melt appropriately colored Jolly Ranchers and pour them onto the wax paper, using the image as a guide.