Cheddar And Gruyère Grilled Cheese

"Gruyère + cheddar grilled cheese for the win on this lovely Saturday afternoon ????"
-- @bornandbredinbrooklyn
Makes one sandwich Ingredients: 2 slices white bread 1/4 cup grated Gruyère cheese 1/4 cup grated cheddar cheese butter, as needed mayo, as needed kosher salt optional extras: fig jam, apple slices, caramelized onions Heat a cast iron skillet over medium low heat. Add the butter and allow it to melt a little. Sprinkle with the kosher salt. Coat bread with a very thin layer of mayo (don't worry you won't taste it! It just helps to get the perfect golden brown color). Add one slice of bread (mayo side down) to the pan with the butter. Add cheese and any extras you may want, followed by the top slice of bread. Cook until cheese starts to melt, and flip. Cook until golden brown on the second side and cheese has melted through. Enjoy!