Messy? Maybe. Worth it? Yes. The secret to fully loaded nachos that won’t fall apart in your lap? A mixture of salsa and refried beans acts like the “glue” to help the toppings stick to the tortilla chips.
Preheat oven to 400°F. Cook chorizo and onion in a large nonstick skillet over medium, stirring often with a wooden spoon to crumble, until chorizo is well browned and onion is tender, about 8 minutes. Drain on a plate lined with paper towels.
Stir together refried beans and 1 cup of the tomatillo salsa in a small saucepan. Cook over medium-high, stirring often, until hot, about 3 minutes.
Line a large rimmed baking sheet with aluminum foil. Arrange chips in a single layer on foil. Top chips evenly with chorizo mixture, bean mixture, and cheeses.
Bake in preheated oven until cheeses melt and just begin to brown in places, about 8 minutes. Remove from oven, and top with avocado, jalapeño, sour cream, cilantro, and remaining tomatillo salsa. Drizzle with hot sauce, if desired.