Start by chopping your fresh pineapple into small pieces or lightly pulse in a food processor. You want it chunky, but not too coarse. Measure out 4 cups.

In a heavy-bottomed saucepan, combine the chopped pineapple, sugar, and lemon juice. Stir until evenly mixed.

Bring the mixture to a simmer over medium heat, stirring occasionally. Once it starts to bubble, reduce to medium-low and simmer gently for 45–55 minutes. Stir frequently, especially toward the end, to prevent sticking or burning.

The jam is ready when it thickens and coats the back of a spoon. You can test by placing a small spoonful on a chilled plate—if it wrinkles slightly when pushed with your finger, it's set.

Remove from heat and let cool for 10–15 minutes. Spoon into clean jars and let cool completely before sealing. Store in the refrigerator for up to 3 weeks or freeze for longer storage.