Preheat your oven to 375°F (190°C). Lightly grease a 12-cup mini muffin tin with olive oil or cooking spray. Alternatively, if using an air fryer, preheat to 350°F (175°C).

Using a 3-inch round cookie cutter, cut out 12 circles from the corn tortillas. You may need to overlap cuts or use a few extra tortillas to get 12 perfect circles. Discard or save scraps for another use.

Gently press each tortilla circle into the cups of the mini muffin tin, molding them to form a cup shape. Bake in the preheated oven for 8-10 minutes, or until lightly golden and crisp. If using an air fryer, cook in batches for 4-6 minutes at 350°F (175°C), until crisp. Remove from oven/air fryer and set aside.

While the tortillas are baking, heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it apart with a spoon, until fully browned and no pink remains, about 5-7 minutes. Drain any excess grease.

Stir in the taco seasoning and water. Bring to a simmer and cook for 2-3 minutes, stirring occasionally, until the liquid has mostly absorbed and the meat is well-seasoned. Remove from heat.

Spoon about 1-2 tablespoons of the seasoned ground beef into each crispy tortilla cup in the mini muffin tin.

Sprinkle about 1 tablespoon of shredded cheese over the meat in each cup.

Return the muffin tin to the oven (still at 375°F / 190°C) and bake for an additional 3-5 minutes, or until the cheese is melted and bubbly. Watch carefully to prevent burning the tortilla edges.

Carefully remove the mini Mexican Hat Appetizers from the muffin tin. Garnish each with a sprinkle of diced tomatoes and fresh cilantro. Add a small dollop of sour cream or guacamole just before serving.

Serve immediately while warm. Enjoy your festive fiesta bites!