01 -
Heat a skillet over medium to medium-low heat.
02 -
Spread butter on one side of each slice of bread.
03 -
Place one slice of bread in the skillet, buttered side down.
04 -
Evenly distribute half the Gruyère on the bread, then layer with ham, caramelized onions, and sage.
05 -
Top with remaining Gruyère and cover with the second slice of bread, buttered side up.
06 -
Cook for 5 to 7 minutes until the bread is golden brown, then flip and cook the other side for an additional 5 to 7 minutes.
07 -
Remove from the skillet and serve immediately while hot.