Grilled Cheese Deluxe Recipe

Cook onions

Heat a medium skillet over medium heat. Add 1 tablespoon olive oil and 1 teaspoon butter. When butter melts, add the thinly sliced onion and 1/4 teaspoon salt. Stir to coat.

Cook onions, stirring every 2–3 minutes, until soft and deep golden brown, about 20–25 minutes. If onions look dry or are browning too quickly, lower heat and add a splash of water. For a touch of sweetness and faster color, sprinkle 1/2 teaspoon brown sugar after 10 minutes.

When onions are deeply browned and jammy, remove from heat and set aside to cool slightly. Yield should be about 1/2 cup.

Prepare the bread: Spread mayonnaise on one side of each bread slice (this will be the interior, for extra browning and tang). On the other interior side of two slices, spread Dijon mustard thinly.

Butter the exterior: Spread the remaining 3 tablespoons of unsalted butter evenly on the outside faces of the two sandwich halves (about 1 1/2 tbs per side). For even melting, soften butter to room temperature before spreading.

Layer the cheese and add-ins: On the two slices with mayonnaise/mustard, divide the cheeses evenly. Start with a layer of shredded sharp cheddar (about 1/2 cup per sandwich), then add 1/4 cup Gruyère and 1/4 cup fontina per sandwich. Sprinkle 2 tablespoons of caramelized onions over the cheese layer, then add 2–3 thin tomato slices (pat dry with paper towel first). If using, add 2 slices chopped bacon and 3 basil leaves per sandwich.

Close the sandwiches: Place the buttered exterior slices on top, butter side out, pressing gently to compress the fillings into an even layer.

Heat a large nonstick or cast-iron skillet over medium-low heat. The low temperature allows the cheese to melt without burning the bread.

Place one or two assembled sandwiches (depending on skillet size) in the skillet. Cook for 3–4 minutes on the first side, pressing lightly with a spatula or a heavy pan to ensure even contact. When the bread is golden brown and a crust has formed, flip the sandwich carefully.

Cook the second side for another 3–4 minutes, pressing again and reducing heat slightly if the bread is browning too fast. Total cook time should be 6–8 minutes until the cheese is fully melted and the bread is deep golden brown.

If cheese is not fully melted by the time the second side is golden, cover the skillet with a lid for 1–2 minutes to trap heat and finish melting, or transfer sandwich to a preheated 350°F (175°C) oven for 3–4 minutes.

Remove sandwiches from skillet and let rest 1 minute. Slice each sandwich in half on a diagonal and serve immediately.