Preheat George Foreman grill by plugging it in, or setting it to MAX, 300°F or setting 3. Butter one side of each slice of bread and flip 4 pieces of bread over (butter side down).
Slice Fontina into 12 pieces (3 pieces of cheese per sandwich) and top butter side down bread.
In a small bowl, add blueberries, cinnamon, sugar and vanilla. Mash blueberries with fork to release some of juices. (Note: Blueberries don’t need to be smooth, but roughly mashed.)
Spread mashed blueberries over cheese and top with cooked bacon.
Place remaining slice of bread (butter side out) on top of bacon.
Place on preheated grill and close lid. Grill for 7-9 minutes until cheese is melted and bread is crispy.
Note: if grilling on Indoor/Outdoor grill, grill for 7 minutes per side.