Prep the oven and pan: Preheat the oven to 400°F (200°C). Line a large sheet pan with parchment for easy cleanup.
Set aside.
Brown the beef: Heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it up with a spatula, until mostly browned, about 4–5 minutes. If there’s a lot of fat, spoon off excess, leaving about 1 tablespoon for flavor.
Build flavor: Add the diced onion and cook until softened, 2–3 minutes.
Stir in garlic and cook 30 seconds until fragrant.
Season and simmer: Stir in chili powder, cumin, smoked paprika, oregano, salt, pepper, and red pepper flakes if using. Add tomato paste and cook 30–60 seconds to toast it. Pour in broth or water and simmer 2–3 minutes, stirring, until thick and saucy.
Taste and adjust seasoning.
Layer the chips: Spread half the chips on the sheet pan. Top with half the beef, half the beans (if using), and half the cheese. Add the remaining chips and repeat with the rest of the beef, beans, and cheese.
This two-layer method helps every chip get something good.
Bake until melty: Put the pan in the oven and bake 6–8 minutes, just until the cheese is fully melted and bubbling. Avoid overbaking or the chips can get too dark.
Add fresh toppings: Remove from the oven and immediately top with tomato, red onion, jalapeño slices, avocado, and cilantro. Dot with sour cream or drizzle with a thinned sour cream if you like.
Finish with a squeeze of lime and serve right away with salsa and hot sauce.