Heat a medium saucepan with high sides on medium heat. Add the blueberries, maple syrup, lemon zest, lemon juice, water, ground ginger if using, and nutmeg if using, and salt to the saucepan.
Cook for approximately 15 minutes, stirring occasionally, reducing heat to low or low-medium to simmer, until blueberries start to break down and release their juices. If the mixture seems too thick, add the water. If you want the thicker compote, add the cornstarch. Set aside to cool slightly before serving. Let cool completely before storage. The compote will thicken as it cools.
Notes
Cook the blueberries just until they start to break down; take care not to overcook them to retain their shape. You want some berries to remain whole for optimal texture.
If the blueberry mixture seems too thick while cooking, add another one to two tablespoons of water. Add a small amount of organic cornstarch if you want a thicker compote.
Once cooled, refrigerate the blueberry compote in an airtight glass container for up to 2 weeks.
Freeze for up to 3 months. Remove it from the freezer and let it thaw in the refrigerator overnight. Once thawed, gently stir it before serving.