Preheat and prep. Set the oven to 425°F (220°C). Line two sheet pans with parchment for easy cleanup. This is where we win the war on sogginess.
Slice the sweet potatoes. Use a sharp knife or mandoline to cut 1/8-inch rounds. Too thick and they'll steam; too thin and they'll burn. Aim for goldilocks.
Season the “chips.” Toss slices with olive oil, salt, pepper, chili powder, and cumin until evenly coated. Spread in a single layer without overlapping.
Roast to crisp. Bake for 12–15 minutes, flip, then bake another 8–12 minutes until edges crisp and centers are tender. Remove any that finish early so nothing burns—be the nacho lifeguard.
Warm the beans and corn. While the chips roast, heat a small skillet over medium. Add beans and corn with a pinch of salt and cumin. Stir 3–4 minutes until warmed. This keeps everything hot when you assemble.
Build the nachos. Transfer the crisped sweet potato rounds to one sheet pan. Overlap slightly to form a sturdy base. Sprinkle half the cheese, add beans and corn, then top with remaining cheese and jalapeño slices.
Broil for melt. Broil on high 1–3 minutes until the cheese is fully melted and slightly browned. Don't walk away; cheese goes from perfect to sad in seconds.
Finish with fresh. Top with salsa, red onion, avocado, and cilantro. Squeeze lime over the whole pan. Add sour cream or Greek yogurt if you want that creamy hit.
Serve immediately. Sheet pan to table. Use a spatula to scoop from the bottom so every plate gets crispy chips and toppings.