Add the blueberries, lemon juice, cinnamon, and 1 cup of water to a medium-size saucepan over medium heat. Cook, stirring occasionally, until boiling.
Reduce heat to medium-low and simmer, stirring often, for about 5 minutes.
In a small bowl mix together the cornstarch and 2 TBSP water until well combined. Slowly stir the cornstarch mixture in with the blueberries. Continue to simmer over medium-low heat until thickened, about 2 minutes.
Ladle into bowls and serve warm topped with yogurt.