Simmer blueberries: In a small saucepan, combine the blueberries and water (if using). Cook over medium-high heat until the berries begin to burst and soften, stirring occasionally. (3-5 minutes).
Sweeten (optional): Taste the blueberry mixture and add your preferred sweetener if desired. Stir until dissolved.
Thicken (optional): If a thicker compote is desired, mix a small amount of cornstarch or tapioca starch with water to create a slurry before adding to the blueberry mixture. Simmer for a few more minutes until the desired consistency is reached. Cornstarch generally creates a clear, glossy texture.
Enhance flavors (optional): Stir in any desired spices, extracts, or citrus zest for a more complex flavor profile.
Cool: Allow the blueberry compote to cool completely before using.