Simple Blueberry Grilled Cheese - Blueberries

Ingredients

• 6 1/2 cups fresh blueberries, coarsely chopped (about 5 pints)
• 1 package granulated fruit pectin for lower-sugar recipes
• 4 1/2 cups granulated sugar, divided
• 1/4 cup Homemade Blueberry Jam
• 8 slices sourdough bread
• 1 cup fresh blueberries
• 1 cup shredded mozzarella cheese
• 1/4 teaspoon salt
• 1/4 teaspoon pepper
• 2 tablespoons butter, at room temperature