01 -
Heat olive oil in a large pot over medium heat. Add diced onions and sauté until softened. Add ground beef and taco seasoning, then cook, breaking it up, until browned and fully cooked. Remove the beef and onions from the pot, leaving some drippings behind.
02 -
In the same pot, melt butter. Sprinkle in flour and whisk for 1–2 minutes until a roux forms. Gradually pour in milk, whisking until smooth and slightly thickened. Add Rotel (with juices) and stir in freshly shredded cheddar cheese until melted and velvety. Mix in sour cream, hot sauce, and a pinch of taco seasoning. Stir well.
03 -
Return the cooked beef and onions to the cheese sauce. Stir together and let simmer on low heat for 10 minutes, until thick and creamy.
04 -
Arrange taco shells on a baking sheet and warm them in a 350°F oven for 5 minutes to crisp up.
05 -
Fill each taco shell generously with the cheesy Rotel beef mixture. Serve hot, with Spanish rice on the side if desired.