Put a pot over medium heat and add the raspberries. Stir in the water and sugar
Stir until all of the sugar has been dissolved
Make sure to stir the mixture often while you heat it to the boiling point
Once it comes to a boil, reduce the heat and stir in the vanilla
Make a slurry out of cornstarch now
Mix the cornstarch and 2 tablespoons of lemon juice in a small bowl until the cornstarch is well combined
Add the cornstarch mixture to the pot and stir until well combined
For four to five minutes, or until the sauce reaches the appropriate thickness, bring to a boil
Remove the pan from the heat and add the butter
Stir until the butter has completely melted and incorporated into the sauce
Add the remaining fresh or frozen raspberries to the raspberry sauce after it has cooled for about 20 minutes
Until the raspberries are equally distributed, mix well
Serve this sauce hot or cold over cheesecake, ice cream, breakfast foods, and other desserts