Preheat the oven: Set to 350°F (175°C). Lightly grease a 9x13-inch baking dish.

Brown the beef: Heat a large skillet over medium-high. Add a little oil, then the ground beef. Break it up and cook until no longer pink, about 6–8 minutes. Drain excess fat if needed.

Add aromatics: Stir in the diced onion and cook 3–4 minutes until softened. Add minced garlic and cook 30 seconds, just until fragrant.

Season the mixture: Stir in 1–2 teaspoons mustard, 1 teaspoon Worcestershire, 1 tablespoon tomato paste (if using), 1/2 teaspoon smoked paprika, and a good pinch of salt and pepper. Taste and adjust seasonings. You want it boldly seasoned.

Soften with cream cheese: Reduce heat to low. Add the softened cream cheese in small chunks. Stir until it melts and coats the beef mixture. This helps bind the casserole and adds richness.

Layer the beef: Spread the beef mixture evenly into the prepared baking dish. Sprinkle chopped pickles and crumbled bacon (if using) over the top. Add half of the shredded cheddar and half of the mozzarella.

Make the custard: In a bowl, whisk together the eggs, heavy cream, 1/2 teaspoon salt, and a few grinds of pepper until smooth. Pour evenly over the beef and cheese layer.

Top with more cheese: Sprinkle the remaining cheddar and mozzarella over everything.

Bake: Place in the oven for 25–30 minutes, until the center is set and the top is lightly golden and bubbling. If you like a deeper color, broil for 1–2 minutes at the end, watching closely.

Rest and garnish: Let the casserole rest 5–10 minutes to firm up. Top with sliced green onions or chives. Add extra chopped pickles or a drizzle of sugar-free “special sauce” if you like.

Serve: Cut into squares and plate with a simple side salad or roasted veggies.