Warm a large, deep skillet or Dutch oven over medium heat. Add olive oil and butter.
When melted, add the diced onion and a pinch of salt. Cook 3–4 minutes until softened.
Add the ground beef. Break it up with a spoon and cook until browned and no longer pink, about 5–7 minutes.
Drain excess fat if needed, leaving about 1 tablespoon in the pan.
Stir in minced garlic (or garlic powder), smoked paprika, onion powder, ground mustard, and black pepper. Cook 30 seconds until fragrant.
Add the tomato paste and cook for 1 minute, stirring, to caramelize slightly. This deepens the sauce flavor.
Pour in the beef broth and Worcestershire sauce.
Scrape the bottom of the pot to release any browned bits. Bring to a gentle boil.
Add the elbow macaroni. Stir well so the pasta is evenly distributed and submerged.
Reduce to a steady simmer, cover, and cook 10–12 minutes, stirring every couple of minutes so nothing sticks. Adjust heat as needed to maintain a gentle simmer.
When the pasta is just tender, pour in the milk. Simmer uncovered for 2–3 minutes to slightly thicken.
If it looks too tight, splash in a bit more broth or milk.
Remove from heat. Gradually sprinkle in the shredded cheddar, stirring until fully melted and creamy. Taste and season with salt and additional pepper as needed.
Add a pinch of red pepper flakes if you like a little heat.
Let it rest 2 minutes to thicken. Garnish with chopped parsley or chives. Serve hot and cheesy.