In a frying pan (or electric, non-stick griddle), melt 3 tablespoons of butter. Make sure butter does not burn. In a small bowl, mix together the peanut butter, honey and cinnamon. Slice the bananas into ¼-inch thick slices. Spread the peanut butter mixture on 4 slices of bread and cover with the banana slices. Meanwhile, heat strips of bacon on griddle. Once the bacon is heated throughout, position in the center of the bread. Top with the remaining 4 slices of bread. Spread the remaining butter on both sides of the sandwiches. Grill the sandwiches until each side is golden brown.