Prep the mushrooms: Gently twist out the stems and set the caps aside. Finely chop the stems. Wipe the caps clean with a damp towel; avoid soaking them.

Preheat the oven: Set it to 400°F (200°C). Line a baking sheet with parchment paper or lightly oil a baking dish.

Sauté aromatics: In a large skillet, heat olive oil or butter over medium. Add onion (or shallots) and chopped mushroom stems. Cook 3–4 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.

Brown the beef: Add ground beef to the skillet. Season with salt, pepper, paprika, Italian seasoning, and red pepper flakes if using. Cook, breaking it up, until browned and no longer pink, about 6–8 minutes. Drain excess fat if needed.

Make it cheesy: Reduce heat to low. Stir in cream cheese and Parmesan until melted and creamy. Remove from heat and fold in half of the shredded cheese.

Fill the caps: Arrange mushroom caps, cavity-side up, on the baking sheet. Spoon the beef mixture into each cap, mounding slightly. Top with the remaining shredded cheese.

Bake: Bake for 15–18 minutes, or until mushrooms are tender and the cheese is bubbly and lightly golden.

Finish and serve: Let them rest 3–5 minutes. Sprinkle with chopped parsley and a crack of black pepper. Serve warm.