Cook the macaroni in a pot of boiling salted water until it is al dente, 7 to 9 minutes.

Heat the oil in a skillet over medium heat. Add the seitan and cook until browned. Add the soy sauce, stirring to coat. Remove from heat and set aside.

In a food processor, process the tofu until smooth.

Add the non-dairy milk, broth, nutritional yeast, cornstarch, lemon juice, mustard, salt, garlic powder, onion powder, turmeric, and pepper. Blend until smooth.

Preheat the oven to 190° C. Lightly oil a large baking dish and set aside.

Drain the cooked macaroni and return it to the pot.

Add the reserved seitan and the sauce mixture and mix well.

Taste and adjust the seasonings, adding more salt if needed.

Transfer the mixture to the prepared baking dish, top with the breadcrumbs, and bake until hot and the crumbs are nicely browned, 25 to 30 minutes.

Serve hot.