Prepare the cheese: If using block cheese, shred the cheese using the large side of a box grater, and set it aside to warm to room temperature. (Having the cheese closer to room temperature helps it melt more easily.) If using pre-shredded cheese, remove the bag(s) from the fridge and set them on the counter to warm to room temperature.
Prepare the pasta: Bring a large pot of unsalted water to a boil. Add the macaroni and follow the directions on the package for al dente pasta.
While the macaroni is cooking, prepare the cheese sauce: In a large saucepan, combine 2 cups of milk with the soy sauce, onion powder, dry mustard, paprika, bay leaf, salt, black pepper, and hot sauce. Place over medium heat, and cook until the mixture comes to a gentle simmer.
In a small bowl or cup, mix the cornstarch with the remaining ¼ cup cold milk. Add the cornstarch mixture to the sauce and stir to combine. Return the sauce to a simmer and cook for 2 to 3 minutes, stirring occasionally. The mixture should thicken slightly.
Remove the saucepan from the heat, discard the bay leaf, and add the shredded cheese. Continue stirring until the cheese is completely melted and no lumps remain.
Add the margarine spread to the cheese sauce and stir until it is completely melted and combined.
Drain the macaroni (do not rinse it), and return it to the pot.
Pour the cheese sauce over the cooked macaroni and stir until everything is coated. Cover the pot with a tight-fitting lid and allow the macaroni and cheese to sit for 5 to 10 minutes, to allow the sauce to thicken before serving.