In a pot heat up blueberries, granulated sugar, lemon juice, vanilla extract and cinnamon. Once it starts bubbling, take it down to a medium heat and let it simmer for 8 minutes. While it cooks, give the blueberries a stir once in a while. When 8 minutes has passed, mix together cornstarch and the water. Then add it to the blueberries and stir it in. Continue stirring for 2 minutes, mashing out the blueberries with the back of the spatula.
250 g blueberries, 50 g granulated sugar, 2 teaspoon lemon juice, 1 teaspoon vanilla extract, ½ teaspoon cinnamon, 2 teaspoon cornstarch, 4 teaspoon water