Boil macaroni in well-salted water until just al dente, 7–8 minutes.
Drain the pasta, shake off excess water, and set aside.
Melt butter in a medium saucepan over medium heat.
Whisk in flour and cook, stirring, until foamy and lightly golden, 1–2 minutes.
Slowly whisk in milk and cream. Simmer, whisking often, until slightly thickened, 3–5 minutes.
Season the sauce with salt, sugar, mustard, paprika, garlic, onion, and pepper.
Remove from heat and stir in American and cheddar until smooth and glossy.
Fold in the cooked macaroni until evenly coated. Splash in a bit more milk if you prefer looser sauce.
Rest 2 minutes to set. Serve warm; add hot sauce to taste if using.