Peel the bananas and mash them in a mixing bowl, leaving a few small chunks for texture.
Transfer the mashed bananas to a medium saucepan. Add sugar, lemon juice, water, and cinnamon (if using).
Heat over medium flame, stirring frequently to prevent burning.
Let the mixture simmer for 15 to 20 minutes, stirring often until it thickens.
When the jam reaches your preferred thickness, take it off the heat.
Let it cool for 5 to 10 minutes.
Spoon the jam into sterilized jars using a funnel and ladle. Seal tightly.
Store in the refrigerator for up to two weeks or freeze for up to three months.
