Heat olive oil in a large skillet over medium-high heat, then add ground chicken, sweet potato, and onion. Cook while breaking up the chicken until it’s browned and the vegetables start to soften. Sprinkle in all spices and salt, stirring well so everything is evenly coated and fragrant.
Pour in about ¾ cup of water and lower the heat slightly. Let the mixture simmer until most of the liquid evaporates and the sweet potatoes are fork-tender. Stir in black beans and cook for a few more minutes until warmed through.
Preheat the oven and spread tortilla chips evenly on a baking sheet. Sprinkle half of the cheese over the chips, then spoon the chicken mixture evenly across. Finish with the remaining cheese so everything melts together.
Place the baking sheet in the oven and bake until the cheese is fully melted and bubbly. Keep an eye on it so the chips don’t over-brown around the edges.
While the nachos bake, mix Greek yogurt, chopped jalapeños, lime juice, and salt in a bowl. Stir until smooth and creamy, tasting as you go to adjust heat and acidity.
Remove the nachos from the oven and drizzle generously with jalapeño yogurt. Top with mashed avocado, cilantro, green onions, and fresh lime juice. Serve immediately for best texture and flavor.