Chop and core the pears with a paring knife and place in a heavy-bottomed saucepan or Dutch oven.
Add the water, lemon juice, vanilla, and cinnamon.
Cover and simmer over medium heat (not high heat!) for 20-30 minutes, stirring occasionally to prevent sticking on the bottom of the pan. The pears are ready when they're completely soft and cooking in their own juices.
Remove from heat and blend with an immersion blender or stick blender, or transfer to a food processor or high-speed blender. Blend until completely smooth. Check post for canning instructions as they differ from this.
Taste and add sweetener if desired. Serve warm or let cool to room temperature and store.
Notes
Really ripe, sweet pears may not need the full 1/4 cup of water. Start with less and add more only if needed. You want just enough liquid to prevent scorching, but not so much that the sauce becomes watery.
Be sure to taste before adding any sweetener, as ripe pears are often naturally sweet enough on their own.
Store in glass jars or plastic containers in the fridge for up to 1 week.
Enjoy cold or warm gently on the stovetop or in the microwave.
Freeze in freezer-safe containers for up to 6 months. This is a good way to preserve extra if you have a bushel of pears.