1In 8-inch skillet, heat oil over medium heat. Add bread crumbs to oil. Cook 2 to 3 minutes, stirring constantly, until golden brown; set aside.
2In 5-quart Dutch oven or saucepan, cook macaroni as directed on package, except add cauliflower florets 5 minutes before end of cook time. Drain; return to Dutch oven.
3Meanwhile, in 1 1/2-quart saucepan, heat oil over medium heat. In small bowl, beat together milk and flour, using whisk, until smooth. Stir milk mixture into oil in saucepan. Cook, stirring constantly, until mixture thickens and bubbles. Remove from heat; cool 3 minutes. Stir in cheese, salt, nutmeg and pepper just until cheese melts; stir in pimientos and 1 tablespoon basil.
4In Dutch oven, cheese mixture into cooked macaroni until well combined. For each serving, sprinkle macaroni with about 1 tablespoon crumb topping and about 1 teaspoon basil.