Slice the avocado in half, remove the pit, and scoop out the flesh into a bowl.
Mash the avocado with a fork.
Add chopped tomatoes, jalapeño, onions, and finely chopped cilantro to the mashed avocado.
Squeeze the juice of the key lime into the bowl and stir everything together until well combined.
Season the guacamole with salt and pepper to taste.
Butter one side of two slices of bread.
On the non-buttered side of each slice, place half of the Monterey Jack cheese, followed by half of the guacamole mixture.
Top each sandwich with the remaining cheese slices and the remaining slices of bread, buttered side facing out.
Cook the sandwiches at 325°F for four minutes on each side.
Notes / Tips / Wine Advice:
Wine Advice:Pair this delicious sandwich with a glass of crisp and fruity Sauvignon Blanc or a light-bodied Pinot Grigio. The wine's acidity will complement the creamy guacamole and the richness of the Monterey Jack cheese. Enjoy the delightful combination of flavors!