In-N-Out Grilled Cheese and Loaded Fries

Pro tips

• Butter both sides of bread generously and toast over medium heat for 2–3 minutes per side to achieve a crispy exterior without burning.
• Add cheese after toasting and cover the skillet briefly to trap heat and melt the cheese evenly without overcooking the bread.
• Caramelize onions low and slow—rushing them on high heat produces raw, bitter results instead of sweet, tender layers.
• Use a spatula to press gently while cooking, which promotes even browning and cheese adhesion without flattening the sandwich.

Substitutions

• American cheese → Cheddar or Swiss (richer flavor, slightly slower melt)
• Butter → Mayo (creates crispness from the inside; use less to avoid greasiness)

Storage & make-ahead

Store leftover grilled onions and spread in separate airtight containers for up to 3 days; reheat the sandwich in a skillet over low heat to restore crispness.

What spread is used on the fries?

The spread is In-N-Out's signature sauce, which is a Thousand Island-style blend. You can replicate it with mayo, ketchup, relish, and a touch of pepper.

How do you get the grilled onions soft and caramelized?

Cook sliced onions in a skillet over medium heat with butter for 10–15 minutes, stirring occasionally, until golden and tender.

What cheese works best for this sandwich?

American cheese melts smoothly and mimics In-N-Out's texture, but cheddar or Swiss also work well for a stronger flavor.

Can you meal-prep this?

The sandwich is best served fresh. Prepare grilled onions and spread ahead and assemble just before serving for optimal crispness.

How do you keep the bread crispy while melting the cheese?

Butter the outside of the bread generously and toast over medium heat until golden before adding cheese, so it melts while the bread stays firm.