In a cast iron skillet over medium-high heat add the olive oil, onion, and jalapeno pepper. Sauté for 2 minutes.
Add the ground beef and break apart with a wooden spoon until evenly distributed in the skillet.
Add salt, chili powder, cumin, chipotle or smoked paprika, garlic powder, dried oregano, and cayenne.
Continue to break apart the meat into small pieces and mix in all the spices. Cook until browned and crumbled into small pieces for 5 to 7 minutes.
Remove from heat and set aside. Adjust the seasonings to taste.
Preheat the oven to 375 degrees F.
Place 12 taco shells flat on a sheet pan and sprinkle evenly with about a tablespoon of shredded cheese. Place in the oven for about 3 minutes until the cheese just begins to melt.
Remove from oven and add 1-2 tablespoons of the beef mixture over the cheese, dividing it among the taco shells. (You might have extra beef mixture leftover.) Place in oven for 3 minutes.
Remove the sheet pan from the oven and using a spatula, fold the tacos in half and gently press. Spray the tacos with avocado oil spray and place them in the oven for two minutes.
When the tacos begin to open, place an empty sheet pan on top of them to weigh them down, and continue to bake for 5 minutes.
Remove the sheet pans from the oven. Carefully, remove the top sheet pan and set it aside.
Flip the tacos, place the other sheet pan on top of the flipped tacos, and return to the oven for another 5 minutes. This will ensure even cooking and crispiness on both sides of the tacos.