Finely dice the onion and tomato. If using green chili, finely chop it and set aside. Coarsely chop the cilantro (reserve 1 tablespoon for finishing).

If you haven't already, boil the potato until tender (about 12–15 minutes), cool, peel and cut into 1/2-inch cubes. Drain and rinse the cooked chickpeas if using canned; set both aside.

Make the Indian spiced mix

Heat 1 tablespoon oil or ghee in a small frying pan over medium heat. Add cumin seeds and mustard seeds. When they begin to crackle (about 30 seconds), add turmeric, red chili powder and garam masala. Stir for 10–15 seconds until fragrant, then add the cubed potato and chickpeas.

Sauté potato and chickpeas with the spices for 3–4 minutes so they pick up flavor. Add salt and chaat masala, stir to combine. Taste and adjust salt or spice if needed. Remove from heat and let cool slightly.

Assemble nachos

Preheat the oven to 200°C (400°F) or set an oven-safe broiler to medium-high if you want a quick melt.

Layer 1 — chips and cheese

Spread half of the tortilla chips in an even single layer on a large ovenproof platter or baking sheet lined with parchment. Scatter half the shredded cheddar and half the shredded mozzarella over the chips.

Layer 2 — spiced mix and veggies

Evenly distribute half of the spiced potato-and-chickpea mixture over the cheese. Sprinkle half of the diced onion and tomato, and a little of the chopped green chili if using.

Repeat layers

Add the remaining chips in another even layer on top and finish with the remaining cheddar and mozzarella. Top with the remaining spiced mix, onions and tomatoes. Press down gently so chips contact the cheese for better melting.

Bake for 6–10 minutes at 200°C (400°F) until cheese is fully melted and bubbling. If using broiler, watch closely and broil for 1–3 minutes until the cheese just browns in spots.

Finish & garnish

Remove the nachos from the oven. Dollop or drizzle spoonfuls of whisked yogurt across the top in a few places (use a spoon to thin to desired consistency if needed).

Spoon tamarind-date chutney and mint-coriander chutney over the nachos in lines or small dollops so each bite can get a mix of sweet and minty flavors. Sprinkle pickled onions and the reserved chopped cilantro.

Squeeze the lime over the nachos to taste and add finely diced fresh green chili if you want more heat. Finish with a scattering of sev or crushed papdi for crunch and an extra pinch of chaat masala if desired.

Serve immediately so chips remain crisp. Provide extra chutneys and yogurt on the side.