In a large skillet over medium heat add 1 pound lean ground beef, 1/2 small onion (chopped), and 2–4 jalapenos (seeded, deveined, diced). Cook, breaking up the beef, until the meat is cooked through and the onion is softened, about 5–7 minutes.
Add 3 garlic cloves (minced) and sauté for about 30 seconds. If there is excess fat in the skillet, carefully drain it off.
Stir in 1 1/2 teaspoons chili powder, 1 teaspoon ground cumin, 1/2 teaspoon smoked paprika, 1/2 teaspoon salt, and 1/4 teaspoon dried oregano. Cook and stir for 30 seconds to combine.
Add 1/2 cup salsa and 8 oz. cream cheese (softened) to the skillet. Reduce heat to medium-low and stir often until the cream cheese is completely melted and the mixture is smooth.
Stir in 1 cup of the freshly grated Pepper Jack cheese until melted and well combined. Remove the skillet from heat and reserve the remaining 1 cup of grated Pepper Jack cheese for assembly.
Lay out the 12 raw medium tortillas. Place a heaping 1/4 cup of the beef-cream cheese filling across the bottom third of each tortilla. Top each portion of filling with a heaping tablespoon of the reserved Pepper Jack cheese. Tightly roll each tortilla around the filling and place seam-side down on a tray; repeat until all 12 are rolled.
Heat a large nonstick skillet over medium heat. Working in batches so the pan is not overcrowded, add the rolled taquitos seam-side down first. Cook, turning carefully, until each taquito is golden brown and crisp on all sides, rotating as needed (about 2–3 minutes per side; adjust time as needed).
Transfer cooked taquitos to a plate and let rest briefly before serving. Serve warm.