Step 1

Using a butter knife, spread a thin layer of the mayonnaise or softened butter on one side of each bread slice, ensuring full coverage up to the edges. Before spreading, make sure the slices are the same size and aligned so that when assembled, the shapes of the bread match up perfectly.

Step 2

Assemble the sandwich in the pan: Preheat a non-stick skillet or cast iron pan over medium heat. Once heated, place one slice of bread in the skillet, mayo/butter side down. Then, layer the 2 slices of cheddar cheese onto the bread, ensuring even coverage (depending on the shape of the bread, you may need to tear the cheese for even coverage). Evenly sprinkle the shredded Gruyère over the cheddar. Place the second slice of bread on top, mayo/butter side up.

Step 3

Cook the sandwich for 3 to 4 minutes on one side, or until it's golden brown and crispy. Using a spatula, carefully flip the sandwich over and cook the other side for another few minutes, or until it's also golden brown and the cheese inside has melted.

Step 4

Remove the grilled cheese from the skillet and place it onto a cutting board. Let it sit for a minute, then cut the sandwich in half using a sharp knife. Serve immediately while it's still warm.

Step 5

Note: Wondering which to use for your grilled cheese—mayo or butter? Mayo spreads easily straight from the fridge and has a higher smoke point, reducing the risk of burning. On the other hand, butter offers a distinct, rich flavor. Either choice has its merits, but for the best of both worlds, you can always use both. For what it's worth, I typically use mayo for ease.

Step 6

Pro Tip: For those who like an extra crispy grilled cheese: Spread a thin layer of the mayo or butter on both sides of your bread slices. Before assembling, lightly toast the inside faces of the bread directly in the pan. Once they've achieved a hint of golden crispness, proceed with the recipe. This ensures a delightful crunch both inside and out.