Preheat oven to 350°F/175°C. Prepare a mini muffin pan with cooking spray, melted butter, or mini muffin liners.
In a large skillet over medium heat, cook the ground beef until almost cooked through. Stir in the taco seasoning and finish cooking. Remove from heat and let cool.
In a large bowl, whisk the eggs, then whisk in the taco meat and 4 ounces (about 1 full cup) of the cheese. Fill the mini muffin cups about 3/4 full and sprinkle the remaining shredded cheese over the tops.
Bake for 15-20 minutes, until puffed and firm to the touch. Let cool in pan for about 10 minutes. Serve with your favorite taco toppings, like salsa, guacamole, olives, and/or sour cream.
Air Fryer Instructions
Cook ground beef in the air fryer: Crumble and spread apart beef in the air fryer basket. Cook at 380°F/190°C for 4 minutes. Stir the beef with a silicone spatula. Add taco seasoning. Cook at 350°F/175°C for 3 minutes.
Whisk eggs and add cheese. Add ground beef.
Place 9-10 silicone muffin liners in the air fryer basket. Add 1/4 cup of mixture to liners.
Cook at 330°F/165°C for 10 minutes. Top with cheese. Cook for an additional 3 minutes.