Cauliflower Mac and Cheese

12 oz macaroni
2 heaping cups cauliflower, trimmed, cored, chopped fine
1 1/2 cups sharp cheddar cheese, packed
3 tablespoons flour
3 tablespoons butter
2 cups milk
1 teaspoon onion powder
1/2 teaspoon garlic powder
pinch cayenne
1 tablespoon yellow mustard
salt to taste
1/2 cup panko breadcrumbs

1. Preheat oven to 350°F. Coat a 3-quart baking dish with cooking spray.
2. Cook macaroni according to package directions and add cauliflower during the last 3 minutes of cooking. Cook until pasta is al dente and drain.
3. Melt butter in a saucepan over medium heat. Add flour, onion powder, and garlic powder, and cook 1 minute, whisking constantly. Slowly whisk in milk and mustard. Increase heat to medium-high, and bring sauce to a boil, whisking constantly. Reduce heat to medium-low, and simmer 2 minutes, stirring frequently. Remove from heat and stir in cheddar cheese. Stir in macaroni and cauliflower. Season with salt and pepper.
4. Transfer to prepared baking dish and top with breadcrumbs. Lightly spray breadcrumbs with cooking spray. Bake 35 minutes, or until top begins to brown and filling is bubbling.