Prep the oven and pan: Preheat your oven to 375°F (190°C).
Grease a 9x13-inch baking dish with butter or nonstick spray.
Cook the broccoli: Steam or microwave the broccoli until crisp-tender—about 3–4 minutes for fresh, 5–6 for frozen. Drain well and pat dry to avoid watery sauce.
Brown the beef: In a large skillet over medium-high heat, cook the ground beef, breaking it up as it browns. Season with salt, pepper, paprika, and Italian seasoning.
If using onion, add it now and cook until soft. Stir in the garlic and cook 30 seconds more. Drain excess fat if needed.
Make the cheese sauce: In a saucepan over medium heat, warm the heavy cream and butter until just steaming.
Whisk in the cream cheese until smooth. Add Dijon and a pinch of salt and pepper. Reduce heat to low and slowly stir in 1.5 cups of shredded cheese until melted and velvety.
Adjust seasoning.
Assemble the bake: Add the broccoli and ground beef to the baking dish. Pour the cheese sauce over the top and gently fold to coat everything evenly. Sprinkle the remaining 0.5 cup of cheese over the surface.
Add red pepper flakes if you like a kick.
Bake: Bake for 18–22 minutes, until the top is bubbly and lightly golden. If you want extra color, broil for 1–2 minutes at the end—watch closely.
Rest and serve: Let it rest for 5–10 minutes so the sauce thickens slightly. Garnish with chopped parsley and serve warm.