Heat a non-stick griddle or frying pan over medium-high heat.
Slather the bread slices with mayo on one side (1 tbsp per piece of bread).
Add butter to the griddle or pan and let melt. Place two slices of bread, mayo-side down in the butter. Top each slice of bread with 1 oz of havarti, cheddar and muenster cheese. Place the remaining slice of bread, mayo-side up on top of the cheese.
Cook the sandwiches until the bread is golden brown and crisp on the bottom, about 2 minutes, then carefully flip over and cook another 2 minutes on the other side, or until golden brown. Once cheese is melted, remove from the pan and enjoy!
Notes
Nutrition facts are for 1 grilled cheese sandwich, totals may vary based on the type of bread and ingredients used.