Add the onion, red bell pepper, poblano pepper, and jalapeno. Cook for about 3-4 minutes until the vegetables are soft. Add the minced garlic and cook for another minute.
Bake in the preheated oven for 35-40 minutes or until the cheese is bubbly and slightly browned. Allow the casserole to cool for a few minutes before serving. Garnish with fresh chopped parsley.