Cut the pineapple into matchsticks and place them in a large bowl.
Add the sugar and mix with a rubber spatula. Let the fruit macerate for 30 minutes.
Transfer the mixture to a pot and cook over medium-high heat.
Once it comes to a boil, stir often and continue cooking until the temperature reaches 220˚F (105˚C).
Add the apple jelly and cook until the mixture reaches 225˚F (107˚C).
To test the set, place a small spoonful on a cold plate—if it wrinkles when pushed, it's ready!
