Bring a large pot of salted water to a boil for the pasta.
In a small bowl, whisk together the chili powder, chipotle powder, cumin, oregano, kosher salt, coriander, and cayenne until evenly combined.
Heat a large skillet or saucepan over medium. Add the ground beef and cook, breaking into small pieces, until mostly cooked through, about 5 minutes.
Sprinkle the spice mixture over the beef, stir to coat, and cook until beef is fully cooked; add a splash of water if the mixture is too dry. Transfer the seasoned beef to a bowl with a slotted spoon and set aside.
Make a flour paste by mixing the 2 tablespoons of flour with 2 tablespoons of the milk. Return the skillet to medium heat and add the remaining milk and the flour paste, then whisk in the sodium citrate until smooth.
Heat the milk mixture to a simmer over medium, whisking occasionally until it begins to thicken slightly.
While the milk is coming to a simmer, add the pasta to the boiling water and cook until al dente (about 1 minute less than package directions), timing so it finishes with the sauce.
Turn off the heat when the milk is simmering and add the shredded cheese a handful at a time, whisking after each addition until fully melted and smooth. If needed, return to very low heat briefly to finish melting.
Drain the pasta, add it to the cheese sauce, and stir until evenly coated. Fold in the cooked ground beef mixture.
Serve the cheesy pasta on a bed of shredded iceberg lettuce or topped with it, and garnish with quartered cherry tomatoes before serving.
