Low-Carb In-N-Out Burger Copycat with Cheesy Onion Buns

INGREDIENTS:

• 1 large red onion
• 1 cup shredded cheddar cheese
• 1 cup shredded mozzarella cheese
• 1 lb ground beef
• 1 tsp salt
• 1 tsp black pepper
• 2 tsp mustard
• 1/4 cup mayonnaise
• 1.5 tbsp sugar-free ketchup
• 2 tbsp dill relish
• 1 tsp white vinegar

Optional Add-Ins:

• Pickled jalapeños for a spicy kick
• Avocado slices for extra creaminess and healthy fats
• Bacon for added crunch and flavor
• Sugar-free barbecue sauce for a smoky twist
• Leafy greens for a fresh element and added nutrients

### INSTRUCTIONS:
1. Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
2. Cut the red onion into thick rings and separate them into individual rounds.
3. On the prepared baking sheet, create small mounds of shredded cheddar and mozzarella cheese. Place an onion round on top of each cheese mound.
4. Bake in the preheated oven for 6-10 minutes, or until the cheese is bubbly and starts to crisp around the edges.
5. While the onion buns are baking, season the ground beef with salt and pepper, then shape it into patties. Spread mustard on both sides of the patties.
6. Heat a frying pan over medium heat and cook the patties for about 4 minutes on each side, or until they reach your desired doneness.
7. To make the spread, mix together mayonnaise, sugar-free ketchup, dill relish, and vinegar in a bowl until well combined.
8. Assemble your burger by placing a beef patty between two crispy cheesy onion buns and topping it with the homemade spread.

### NOTES:
– **Serving Suggestions:** Pair this delicious burger with a side of leafy greens or keto-friendly vegetables like grilled zucchini or a fresh cucumber salad for added crunch and freshness.
– **Tips:** For the crispiest cheese onion buns, keep an eye on them in the oven to prevent burning. If the cheese spreads too much, gently push it back toward the onion ring with a spatula before it cools.
– **Variations:** For a dairy-free option, use plant-based cheese alternatives. For a spicy twist, add hot sauce or cayenne pepper to the beef mixture.
– **Prep Ahead:** The spread can be made in advance and stored in the refrigerator for up to a week. You can also form the patties and refrigerate them overnight for a quick meal prep solution.

Enjoy this healthy, low-carb twist on a classic burger that’s perfect for your keto lifestyle!