Heat the vegetable oil in a saucepan over medium heat. Add the flour and whisk to form a roux. Add chili powder, cumin, garlic powder, onion powder, oregano and pepper; stir briefly to toast the spices. Pour in the chicken stock while whisking, bring to a simmer and cook about 10 minutes until thickened. Adjust salt and pepper to taste.

In a skillet over medium–low heat, warm the oil and sauté the diced onion until translucent (≈4 minutes). Add ground beef, onion powder, cumin, oregano, salt and pepper; cook until beef is browned and cooked through. Remove from heat.

Heat oil in a skillet. One by one, fry each corn tortilla briefly on both sides until slightly crispy at the edges but still pliable. Drain on paper towels.

Assemble stacks: On an oven‑proof plate or dish, lay one tortilla, spoon some sauce over it, add a portion of beef and some cheese. Repeat for 3 layers (tortilla → sauce → beef → cheese). On the top layer, add sauce and cheese but skip additional meat.

Preheat oven broiler (or 350 °F if baking). Place assembled stacks under the broiler for about 5 minutes or until cheese is melted and bubbly.

While stacks bake, fry one egg per serving sunny‑side up (or your preferred doneness).

Remove stacks from oven. Top each with a fried egg, chopped onions, a drizzle of crema, and optional lettuce/tomato/queso. Serve immediately.