Street Treat : Indian Bun Omelette

Name: Street Treat : Indian Bun Omelette
Ingredients: For the Omelette; 3 Egg Whites; 5 Cherry Tomatoes, halved; 1 Small Red Onion, diced; 1 Green Chili, finely chopped; 1/2 cup Baby Spinach, roughly torn; 1/4 teaspoon Red pepper flakes; 1/2 teaspoon Chaat Masala; 1/4 teaspoon Garam Masala; 2 tablespoons Light Olive Oil or Unsalted Butter; 1 teaspoon Whole Milk; 2 tablespoons Aged Cheddar / Gouda, grated; 2 tablespoons Fresh Cilantro, chopped (with stalk); Salt & Pepper to taste; Others; 1 Challah Roll / Burger Bun / Soft Bread Roll; 1 teaspoon Softened Butter; 1 teaspoon Cilantro Chutney / Hot Sauce