Mash blueberries with a potato masher (machine mashing makes a weird textured end product)
Add all the ingredients into a saucepan and cook at medium-low heat for two hours. It is going to reduce a lot over time and even start to boil near the end. I left it at the same temperature the entire time stirring about every twenty minutes for the first hour, every ten the second hour, and every minute for the last ten minutes.
After two hours pour the mixture into a food processor or blender and puree it.
Then strain (2 times please) the sauce and enjoy!