Start by bringing 8 cups of water to a boil in a large pot.
Once the water is boiling, add the chopped cauliflower florets and uncooked elbow macaroni. Cook for about 8-10 minutes, until the pasta is al dente and the cauliflower is tender.
Carefully drain the cooked pasta and cauliflower in a colander. Set aside.
In the same pot, reduce the heat and add 1 1/2 cups of milk. Gradually whisk in 3 tablespoons of flour, stirring continuously to avoid lumps.
Once the mixture is thickened, add 2 cups of Cheddar shreds, 1/2 teaspoon salt, and a dash of pepper if desired. Stir until the cheese is melted and the sauce is smooth.
Gently fold the drained pasta and cauliflower back into the cheese sauce, ensuring everything is well coated.
Preheat your oven to 350°F (175°C). Grease a baking dish with oil, butter, or oil spray.
Pour the cauliflower mac and cheese mixture into the prepared baking dish. Sprinkle the top with 1/4 cup of Italian breadcrumbs.
Place the baking dish in the oven and bake for about 20-25 minutes, until the top is golden brown and crispy.