Balsamic Blueberry Grilled Cheese Sandwich

In a small saucepan, combine blueberries, sugar and vinegar. Turn on medium heat and let come to a slow boil. Use a utensil to crush berries as you stir. After boiling for about 5 minutes, pour mixture into a mesh strainer and let the juice syrup separate from the solid berries. Save the syrup for cocktails, pancakes or both! Spread blueberries onto a piece of bread, top with cheese, some spinach, then more cheese! Sprinkle with fresh ground pepper. Top with your other slice of bread and toast. Enjoy!