Ingredients

2   slices (1/2-inch-thick) sourdough, multigrain or another hearty bread
4   slices thick-cut bacon, cooked crisp
4   slices Cheddar
1/2   Granny Smith apple, cored, sliced thin
Roasted Red Onion Mayo, recipe follows
Butter

Roasted Red Onion Mayo:  
1 medium red onion, chopped
2 teaspoons olive oil
Salt and pepper
1-cup mayonnaise

Directions

Preheat a seasoned grill pan or griddle over medium heat. Assemble this sandwich just as you would a traditional grilled cheese sandwich: spread 1 slice of bread with some Red Onion Mayo, then top with 2 slices Cheddar, the bacon, the apple slices, then 2 more slices of Cheddar, finishing with another mayo-slathered slice of bread. Butter the outsides of the bread and transfer to the hot grill. Grill about 3 minutes per side, since this sandwich is so thick. Remove to a cutting board and cut the sandwich in half on the diagonal to serve.

Roasted Red Onion Mayo:  

Preheat oven to 375 degrees F.

On a small-rimmed baking sheet, toss the red onion, olive oil, salt and pepper together. Roast in the oven for 25 to 30 minutes until the onion is very soft, stirring occasionally. Remove from oven and let cool. Transfer to a food processor and buzz until finely chopped. Add the mayo and pulse until smooth and combined.

Recipe Courtesy of Paula Deen