01 -
Preheat oven to 375°F. Lightly grease a 9×9-inch baking dish or similar casserole dish.
02 -
Cook the pasta according to package instructions until al dente. Drain and set aside.
03 -
In a medium saucepan over medium heat, whisk flour and milk together until smooth and slightly thickened, about 3–4 minutes.
04 -
Reduce heat to low. Stir in Greek yogurt, shredded cheeses, Dijon mustard, garlic powder, onion powder, salt, and black pepper. Mix until cheese melts and sauce is smooth. If using, stir in steamed cauliflower puree.
05 -
Pour sauce over cooked pasta and mix thoroughly to coat evenly.
06 -
Spoon mixture into prepared baking dish and spread evenly.
07 -
Mix breadcrumbs with olive oil or melted butter and sprinkle evenly over pasta.
08 -
Bake uncovered for 20–25 minutes until topping is golden and bubbly.
09 -
Allow dish to cool slightly for optimal texture and flavor before serving.