Soak cashews in water for an hour or boil in water for 5 minutes. If you are using a high-speed blender, then you don't need to soak them.
Drain cashews and add to your blender bowl with water, coconut milk, and blend until smooth and creamy.
Add cornstarch, nutritional yeast flakes, onion powder, garlic powder, red bell pepper, and sea salt. Process until creamy. If your sauce is gritty, then you can repeat the blend until it is creamy.
Boil pasta according to package directions.
In the meantime, add the torn pieces of bread to a food processor or blender and process until crumbly. Next, transfer to a bowl and add the melted butter.
Once the pasta is boiled, drain and add the vegan cheese sauce and stir to coat.
Scoop out mac and cheese into the prepared casserole pan. Top with the breadcrumbs mixture followed by vegan cheese shreds.
Bake for about 20 minutes or until the top is golden brown and crispy.
Remove from the oven, cool slightly before serving. Enjoy!