Preheat the oven to 375°F (190°C) and line a large baking sheet with parchment paper. Make sure the parchment lies flat and the baking sheet has enough room to keep the cheese rounds separated.
Combine the shredded cheddar and grated Parmesan in a bowl. Divide the cheese mixture into 8 portions of approximately 30 grams each and place each portion on the parchment, spreading it into a loose 4–5-inch circle with space between each round.
Bake the cheese rounds for approximately 6–9 minutes, watching closely. Remove them when the cheese is completely melted, bubbling, and golden around the edges but not deeply browned throughout.
Allow the baked cheese rounds to cool for approximately 30–60 seconds. While they are still warm and flexible, carefully lift each round with a thin spatula and drape it over the bottom of an upside-down small bowl or ramekin. Gently press the sides down to form cups.
Allow the cheese cups to cool on the molds for 5–10 minutes, or until completely firm and crisp. Carefully remove each cup from the mold and set aside.
In a small bowl, combine the chili powder, cumin, smoked paprika, garlic powder, onion powder, oregano, black pepper, and sea salt.
Heat a large skillet over medium-high heat and add the ground beef. Break it into small pieces and cook until browned and fully cooked, allowing some of the beef to sit undisturbed briefly so it develops browned edges.
Add the prepared spice mixture and 1 tablespoon water to the beef. Stir thoroughly and cook for another 1–2 minutes until the seasoning is evenly distributed and the excess moisture has cooked away. Drain excess grease if necessary.
Slice the jalapeño, chop the cilantro, dice the avocado, and prepare the lime juice while the beef finishes cooking.
Place the cooled cheese cups on a serving platter and spoon a small amount of warm taco beef into each cup. Avoid overfilling so the cheese shells remain crisp and easy to pick up.
Add a small spoonful of sour cream, followed by diced avocado, sliced jalapeño, and chopped cilantro. Finish each cup with a small squeeze of fresh lime juice.
Serve immediately for the best contrast between the crisp cheese shell, warm seasoned beef, cool sour cream, creamy avocado, and fresh toppings.