• Preheat oven to 350°F/175°C. Spray the bottom of a 9x12 pan with a light coating of vegetable cooking spray.
• Add the 2 slices of bread (for the topping) to the oven to toast them as the oven heats. Check them at 10 minutes to make sure they don't burn.

For the Pasta:

• Cook the pasta according to the package directions. Reserve 1 ½ cups of the cooking water, then strain the rest of the water and rinse the pasta. Transfer to a 9x12 baking dish and use a spoon to distribute it equally across the pan (so it doesn't clump together). Set aside.

For The Chickpea Cheese Sauce:

• Combine cooked chickpeas with chopped carrots, nutritional yeast flakes, lemon juice, garlic powder, onion powder, miso paste (or soy sauce), olives, olive oil, vegetable broth, and cornstarch in a blender. Pulse in short bursts to roughly break down the ingredients. Scrape down the side of the blender jar, then pulse again, gradually increasing the speed. Add 1 ½ cups of the pasta cooking water and blend again until smooth. Give the sauce a taste and add salt and pepper as desired.
  
• Transfer the smooth chickpea mixture into a saucepan over medium heat. Cook until it begins to boil, then reduce heat to a simmer. Cook for 2 minutes, until the mixture thickens.
  
• Pour the chickpea cheese sauce over the pasta and stir to combine.
  
• Add any of these optional add-ins to the Mac and cheese: 1 cup of small broccoli florets, 1 cup of small broccoli florets, 1 cup of vegan crumbles.

For the Breadcrumb Topping:

• The bread should be toasted and very firm at this point. Break it into pieces and add it to a food processor along with the other topping ingredients. Pulse for 30 seconds and repeat until crumbs form.
• Pour the crumb mixture evenly over the top of the pasta in the baking dish. Bake for 30 minutes.
  
• Remove from the oven and allow the mixture to cool slightly before serving.