In a mixing bowl, whisk the eggs together with the chopped onion, green chili, cilantro, turmeric, red chili powder, salt, and black pepper until frothy.

Heat 1 tablespoon of butter in a large non-stick frying pan over medium heat.

Pour half of the egg mixture into the pan, swirling it to coat the bottom evenly.

Immediately place two slices of bread into the wet egg mixture side-by-side, then quickly flip them so both sides are coated in the raw egg.

Let the omelette cook for about 2 minutes without moving it, until the bottom is set and golden brown.

Carefully flip the entire omelette structure (with the bread embedded) over to the other side.

Place a slice of cheese on top of each piece of bread.

Fold the overhanging edges of the omelette inward over the bread to create a square shape.

Fold one slice of bread over the other to form a sandwich stack.

Press down gently and cook for another minute until the cheese melts and the bread is toasted, then serve hot.