Heat a large pot over medium, then drizzle in the olive oil. Once it’s shimmering, toss in the diced onion and sauté until soft and see-through—about 6 minutes. Add the garlic and cook for another 30 seconds, just until your kitchen smells amazing.
Add the ground beef, season it with salt and pepper, and break it up with a wooden spoon as it cooks. Let it brown until cooked through.
Stir in the tomato paste and sugar, and seasonings until the beef is coated and everything smells rich and toasted.
Pour in the beef stock and bring the mixture to a boil. Add your pasta and let it cook, stirring now and then, until perfectly al dente—about 8 to 10 minutes, depending on your pasta shape.
Take it off the heat and stir in the shredded cheddar and half the chives. Stir until the cheese melts into that dreamy sauce.
Scoop into bowls and finish with the rest of the chives. Dinner = done.