• Preheat oven to 375.

  Slice the eggplant, zucchini, red onion, and Roma tomatoes. Set aside.
  

For the Sauce

• Heat olive oil in a cast iron skillet over medium heat.

  Add onions, garlic, and peppers, and saute until soft and fragrant.
  
• Add crushed tomatoes, basil, and salt and pepper.
  

For the Ratatouille

• Place sliced vegetables on top of the sauce in a spiral shape around the pan and into the center.

  Drizzle lightly with olive oil and top with salt and pepper.
  
• Cover with aluminum foil and bake for 40 minutes.

  Remove foil and bake for 20 more minutes.
  
• Serve hot over pasta or as a stand-alone dish.