In a large pot, bring salted water to a rolling boil. Add the penne pasta and cook per package instructions until al dente—about 10–12 minutes. Reserve ½ cup pasta water, drain, and set aside.

Place a deep skillet over medium-high heat and drizzle in the olive oil. Add the ground beef, breaking it up. Season with salt and pepper, and cook until browned, about 5–7 minutes. Transfer to a plate, leaving drippings.

In the same skillet, reduce heat to medium and toss in the red bell pepper and onion. Sauté for 3–4 minutes until softened. Stir in garlic and cook for 30 seconds until aromatic.

Pour in heavy cream and whole milk. Add the Velveeta and cream cheese. Stir over low heat until cheeses melt and the sauce is smooth, about 3–5 minutes.

Sprinkle in Cajun seasoning, smoked paprika, red pepper flakes (if desired), and grated Parmesan. Stir to combine evenly.

Return the cooked beef to the skillet, mixing thoroughly into the creamy sauce. Simmer for 2–3 minutes.

Add the drained penne to the skillet, tossing until coated. If thick, add reserved pasta water gradually.

Turn off heat, plate, and garnish with parsley and extra cheese if desired. Serve hot.