Cook bacon until crisp and set aside to drain. In a separate skillet on medium heat, melt enough butter to coat pan. Thinly slice 4 pieces of the loaf on the diagonal and butter one side of each slice. Place bread slices in pairs, unbuttered side down, in skillet and layer cheese slices on the buttered side of each piece of bread. Cook until cheese is beginning to melt, being careful not to burn. Place 2 slices of bacon on 1 side of each sandwich and spread jam on the other side. Put sandwich together in the skillet and finish melting cheese. Sandwiches can be moved to oven to keep warm.