Keto Bunless Bacon Cheeseburger Casserole with Special Sauce

Why You’ll Love This Recipe

• All the flavors of a bacon cheeseburger without the bun—rich, savory, and satisfyingly low-carb.
• Set-it-and-forget-it casserole that feeds a crowd and reheats like a dream.
• Custard keeps the beef ultra-juicy while cheddar melts into a golden, bubbly top.
• “Special sauce” and dill pickles deliver that classic burger-shop tang.

Grocery List

• Produce: 1 medium yellow onion, dill pickles (plus relish for sauce), optional lettuce and scallions/chives for garnish
• Dairy: Sharp cheddar, heavy cream, butter, eggs
• Pantry: Ground beef, thick-cut bacon, yellow mustard, sugar-free ketchup, apple cider vinegar, smoked paprika, garlic powder, onion powder, kosher salt, black pepper, optional Worcestershire or coconut aminos, sesame seeds (optional)

Full Ingredients

For the Casserole

• 2 lb (900 g) ground beef, 85–90% lean
• 8 slices thick-cut bacon (about 8 oz/225 g), chopped
• 1 medium yellow onion (about 8 oz/225 g), thinly sliced
• 1 tbsp unsalted butter or ghee
• 1 cup dill pickle chips, chopped, plus 2 tbsp pickle brine
• 10 oz (about 2.5 cups) sharp cheddar cheese, shredded, divided
• 1 tsp kosher salt
• 1/2 tsp freshly ground black pepper
• 1 tsp smoked paprika
• 1 tsp garlic powder
• 1 tsp onion powder
• Optional: 2 tsp Worcestershire sauce or coconut aminos (sugar-free)

For the Egg-and-Cream Custard

• 6 large eggs
• 1 cup (240 ml) heavy whipping cream
• 1 tbsp yellow mustard (or Dijon)
• 1/4 tsp fine sea salt
• 1/4 tsp freshly ground black pepper

For the Special Sauce

• 1/2 cup mayonnaise
• 2 tbsp sugar-free ketchup
• 1 tbsp yellow mustard
• 2 tsp dill pickle relish (no sugar added) or very finely minced dill pickles
• 1 tsp apple cider vinegar
• 1/4 tsp smoked paprika
• 1/8 tsp garlic powder
• Optional: 1/2 tsp erythritol or allulose, to taste
• Pinch kosher salt, to taste

For Serving (Optional)

• Shredded iceberg or romaine lettuce
• Extra chopped dill pickles
• Sliced scallions or chopped chives
• Sesame seeds

Step-by-Step Instructions

Step 1: Preheat and prep the pan

Preheat the oven to 350°F (175°C) with a rack in the center. Grease a 9×13-inch (3-quart) baking dish with butter or a little avocado oil. If your dish tends to bubble, set a rimmed sheet pan on the lower rack to catch any drips.

Step 2: Caramelize the onions

Heat a large skillet over medium heat. Add the butter, then the sliced onion and a pinch of salt. Cook, stirring occasionally, until the onion is soft and deep golden, 12–18 minutes. If brown bits build up, splash in 1–2 tablespoons of water to deglaze. Transfer onions to a bowl.

Step 3: Crisp the bacon

In the same skillet, cook the bacon over medium heat until evenly crisp, 8–10 minutes. Transfer to a paper towel–lined plate and chop into bite-size pieces. Pour off all but 1 tablespoon of the bacon drippings from the skillet.

Step 4: Brown and season the beef

Add the ground beef to the skillet with the reserved drippings. Cook over medium-high heat, breaking it up with a spoon, until no pink remains, 6–8 minutes. Season with kosher salt, pepper, smoked paprika, garlic powder, and onion powder. Stir in the Worcestershire (or coconut aminos) and the 2 tablespoons pickle brine; simmer 1–2 minutes until most liquid evaporates. Remove from heat.

Step 5: Whisk the custard

In a mixing bowl, whisk the eggs, heavy cream, mustard, sea salt, and pepper until completely smooth and slightly frothy. This custard is what binds the casserole and keeps it tender and juicy.

Step 6: Assemble and bake

Spread the seasoned beef evenly in the prepared baking dish. Top with the caramelized onions, 3/4 cup of the chopped pickles (reserve the rest for garnish), and half of the chopped bacon. Sprinkle 1.5 cups of the shredded cheddar over the top. Pour the custard evenly across the dish, nudging it into corners so it settles. Finish with the remaining cheddar and bacon. Bake until the custard is just set in the center (165°F on an instant-read thermometer), edges are bubbly, and the top is golden, 20–25 minutes. If you prefer deeper browning, broil for 1–2 minutes, watching closely.

Step 7: Make the special sauce and finish

While the casserole bakes, whisk together all the special sauce ingredients in a small bowl; adjust salt and sweetness to taste. Let the casserole rest for 10 minutes before slicing so the custard firms. Serve warm with a light drizzle of special sauce and garnish with the remaining pickles, shredded lettuce, scallions/chives, and a pinch of sesame seeds if desired.

Pro Tips

• Use 85–90% lean beef for the best balance of flavor and moisture. Drain excess fat only if your beef is very fatty.
• Shred your own cheddar from a block for superior melt and fewer additives.
• Pickle brine is the secret: it deglazes the pan and adds classic burger tang without extra carbs.
• Do not overbake. Pull the casserole when the center is set but still slightly jiggly; it will firm up as it rests.
• Caramelize the onions patiently—golden, jammy onions add incredible depth with minimal carbs per serving.

Variations

• Jalapeño Popper: Add 4 oz softened cream cheese to the custard and 2–3 thinly sliced jalapeños; swap half the cheddar for pepper jack.
• Mushroom Swiss: Sauté 12 oz sliced cremini mushrooms in butter; layer with the beef and use sliced Swiss instead of cheddar. Omit pickles; add a pinch of thyme.
• Big Burger Bar: After baking, top with shredded iceberg, more pickles, and sesame seeds; serve with extra special sauce on the side.

Storage & Make-Ahead

Refrigerate cooled leftovers in an airtight container for up to 4 days. Reheat individual portions in the microwave (60–90 seconds) or rewarm the whole casserole, covered, at 325°F (165°C) for 15–20 minutes. Freeze tightly wrapped squares for up to 2 months; thaw overnight in the fridge before reheating. Make-ahead: Assemble up to 24 hours in advance, cover, and refrigerate. Bake straight from the fridge, adding 5–10 minutes to the bake time. Special sauce keeps in the fridge up to 1 week.

Nutrition (per serving)

Approximate values, including about 2 teaspoons special sauce: 680–700 calories; 57 g fat; 6 g total carbs (about 4 g net); 39 g protein. Actual values will vary with brands and garnishes.