Slice cooled loaf.
Spread peanut butter and jelly on one slice. Top with another slice of bread. Spread the top of the sandwich with butter. Heat skillet to medium and place sandwich in the skillet, buttered side down.
While sandwich is cooking, spread remaining side with butter. When the sandwich is toasted to a golden brown, turn over and toast the other side.
Repeat to make as many sandwiches as desired. Remove from skillet and serve warm.