Brown the Sausage: In a large skillet, heat 1 tablespoon of olive oil over medium heat until shimmering. Add the Italian sausage, breaking it into pieces as it cooks. Sauté for 5-7 minutes until the sausage is browned and cooked through, releasing its savory aroma. Once browned, transfer the sausage to your slow cooker, leaving any drippings in the skillet.

Sauté Aromatics: In the same skillet, add a chopped onion and 2 minced garlic cloves. Sauté over medium heat for about 3-4 minutes, stirring occasionally until the onion becomes translucent and fragrant. Pour the mixture into the slow cooker with the sausage.

Combine Ingredients: Add sliced carrots, diced potatoes, chopped bell pepper, and zucchini to the slow cooker. Pour in a can of diced tomatoes (with their juices) and 2 cups of vegetable broth. Sprinkle in dried oregano, dried basil, and season with salt and pepper to taste. Stir everything together until well combined.

Slow Cook: Cover the slow cooker with its lid and set it to cook on low for 6-8 hours or high for 3-4 hours. Let the magic happen!

Finish & Serve: About 15 minutes before serving, add 1 cup of frozen peas to the slow cooker without stirring. Cover again and let them heat through. Once ready to serve, ladle the casserole into bowls and garnish with freshly chopped parsley.